Pattern inspecting and measuring device and program

ABSTRACT

Provided is a pattern inspecting and measuring device that decreases the influence of noise and the like and increases the reliability of an inspection or measurement result during inspection or measurement using the position of an edge extracted from image data obtained by imaging a pattern as the object of inspection or measurement. For this purpose, in the pattern inspecting and measuring device in which inspection or measurement of an inspection or measurement object pattern is performed using the position of the edge extracted, with the use of an edge extraction parameter, from the image data obtained by imaging the inspection or measurement object pattern, the edge extraction parameter is generated using a reference pattern having a shape as an inspection or measurement reference and the image data.

TECHNICAL FIELD

The present invention relates to a pattern inspecting and measuringdevice for inspecting or measuring a pattern using the position of anedge of an inspection or measurement object pattern, and a computerprogram executed by a computer of the pattern inspecting and measuringdevice.

BACKGROUND ART

In the field of semiconductor manufacturing, inspecting devices andmeasuring devices using a scanning electron microscope (SEM) have longbeen used.

As increasingly finer patterns are transferred on a wafer with theevolution of process rule, the density of patterns formed on the waferalso becomes higher, increasing the number of locations requiringevaluation by dimension measurement. As a result, from the viewpoint ofreducing the evaluation time, there is a growing demand for narrowingthe locations where the risk of defect development is high, i.e.,measurement points that require evaluation with higher magnificationratios, by an inspection involving image acquisition with a relativelylarge field of view (FOV) (acquisition of a low magnification ratioimage) relative to the dimension of the pattern as the object ofevaluation. In addition to the trend toward formation of ever finerpatterns, the dimension of defects to be detected on an image is on adecreasing trend because of the inspection using the low magnificationratio image.

The measuring device is also used for managing exposure conditions forhandling process variations, as well as for evaluating the locations ofhigh risk of defect development using an image acquired at highmagnification ratio. As the pattern becomes finer, the measurement valuevariations permitted for managing the pattern dimension for qualitymanagement purpose are in a decreasing trend. The amount of variationpermitted for exposure conditions for manufacturing non-defectiveproducts is also becoming smaller as the pattern becomes finer. Thus,for the purpose of managing exposure conditions too, the permittedvariations in measurement values are in a decreasing trend.

Further, as the shape of the pattern transferred on the wafer becomesmore complex, the uses are increasing, for both the inspecting deviceand the measuring device, where evaluation of shape as a two-dimensionalfeature rather than evaluation of dimension as a one-dimensional featureis required. In the case of shape evaluation, normally, a given contourshape as an evaluation reference and a contour shape extracted from animage obtained by imaging a pattern as the object of evaluation arecompared. The comparison is inherently one of different types of data ofgeometric information and image information. In addition, there is thefactor of process variations and the like. Consequently, a phenomenonoften develops in which the two contour shapes are different.

Against such background, Patent Literature 1 discloses an example of atechnology for performing inspection by contour shape comparison usingdesign data. According to the technology disclosed in Patent Literature1, the amount of deformation of a pattern is considered separately interms of a global amount of deformation and a local amount ofdeformation, and defect inspection is performed using the local amountof deformation.

CITATION LIST Patent Literature

-   Patent Literature 1: JP 2010-268009 A (the specification of U.S.    Pat. No. 7,660,455)

SUMMARY OF INVENTION Technical Problem

When the technology disclosed in Patent Literature 1 is used, there isthe possibility of false alert.

According to an analysis by the inventor, one cause for this is that the“second contour line” in the technology described in Patent Literature 1is formed by using an edge extracted, with the use of a predeterminedthreshold value, from a profile acquired from an image. According to thetechnology described in Patent Literature 1, when the shape of theprofile is the same regardless of location, the amount of global patterndeformation exhibits a value reflecting an overall thickening of apattern due to discrepancy of the amount of exposure during patternformation from an optimum value. Thus, a desired result can be obtainedby inspection using a local amount of deformation obtained bysubtracting the global amount of pattern deformation from the overallamount of deformation.

However, the shape of the profile obtained from the image may be variedby various factors. For example, there is the influence of variousnoises during image acquisition. Further, because an edge effect appearsin a pronounced manner at a portion with large pattern curvature, theprofile shape varies depending on the shape of the side wall includingroughness, and also depending on the two-dimensional pattern shape. Inaddition, the amount of detected secondary electron is influenced by thecharge state of the sample during imaging. Thus, in the case of a linepattern perpendicular to the direction of electron beam scan, forexample, a profile corresponding to the side wall on the right side anda profile corresponding to the side wall on the left side have differentshapes. Conventional technology, such as the technology disclosed inPatent Literature 1, may be strongly subject to such influence, possiblyresulting in the generation of false alert.

Furthermore, the shape of the profile may differ depending on imagingconditions, such as acceleration voltage and probe current, in additionto the above-described factors. Also, the shape of the profile maydiffer depending on individual differences of the imaging device. Thesefactors mainly have a global influence and may appear not to lead to thegeneration of false alert. However, in the case of inspection based oncomparison with design data, a false alert may be generated due to suchfactors for the following reason. For example, when a contour shapedetermined using a threshold value method and a contour shape generatedfrom design data are compared, what threshold value should be used toextract the contour shape for the comparison is typically designated byan inspection recipe and the like. However, when the shape of theprofile is varied, there is the possibility that a threshold valuedifferent from the pre-designated threshold value becomes an appropriatethreshold value as a result of the variation. In such a case, namely ifthe contour shape is determined using an inappropriate threshold value,a false alert could be generated by the conventional technology, such asthe technology disclosed in Patent Literature 1.

From the above analysis, the inventor considered the nature of theproblem in terms of the fact that, during inspection or measurementusing an edge extracted from a profile, which is acquired from an imageobtained by imaging a pattern as the object of evaluation, with the useof a certain threshold value (more generally, an edge extractionparameter), the threshold value is not necessarily suitable for theinspection or measurement.

In view of the above analysis, there are proposed below a patterninspecting and measuring device and a computer program for the purposeof decreasing the influence of noise and the like and increasing thereliability of inspection or measurement result during inspection ormeasurement using the position of an edge extracted from an imageobtained by imaging a pattern as the object of inspection ormeasurement.

Solution to Problem

In order to solve the problem, the following configurations described inthe claims are adopted, for example.

The present application includes a plurality of means for solving theproblem. For example, in a pattern inspecting and measuring device thatperforms inspection or measurement of an inspection or measurementobject pattern using the position of an edge extracted, with the use ofan edge extraction parameter, from image data obtained by imaging theinspection or measurement object pattern, the edge extraction parameteris generated using a reference pattern having a shape as an inspectionor measurement reference and the image data.

Advantageous Effects of Invention

According to the present invention, during inspection or measurementusing the position of the edge extracted from the image data obtained byimaging the pattern as the object of inspection or measurement, theinfluence of noise and the like can be decreased, and the reliability ofan inspection or measurement result can be increased.

Other problems, configurations, and effects will become apparent fromthe following description of embodiments.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a configuration of a pattern inspecting deviceaccording to a first embodiment.

FIG. 2 is a flowchart of an operation of the pattern inspecting deviceaccording to the first embodiment.

FIG. 3 is a flowchart of an operation concerning a reference contourline forming process as part of an operation of an initial setting unitincluded in an operating device of the pattern inspecting deviceaccording to the first embodiment.

FIG. 4 illustrates a reference edge extraction method and reference edgeselection method in a reference contour line forming process as part ofthe operation of the initial setting unit included in the operatingdevice of the pattern inspecting device according to the firstembodiment.

FIG. 5 is a flowchart of an operation concerning a reference edgeextraction process in the reference contour line forming process as partof the operation of the initial setting unit included in the operatingdevice of the pattern inspecting device according to the firstembodiment.

FIG. 6 is a flowchart of an operation of an edge extraction parametergeneration unit included in the operating device of the patterninspecting device according to the first embodiment

FIG. 7 is a flowchart illustrating an operation concerning a brightnessprofile generation process as part of the operation of the edgeextraction parameter generation unit included in the operating device ofthe pattern inspecting device according to the first embodiment.

FIG. 8 illustrates a brightness profile acquisition direction in thebrightness profile generation process, as part of the operation of theedge extraction parameter generation unit included in the operatingdevice of the pattern inspecting device according to the firstembodiment.

FIG. 9 is a flowchart illustrating an operation concerning an initialparameter calculation process as part of the operation of the edgeextraction parameter generation unit included in the operating device ofthe pattern inspecting device according to the first embodiment.

FIG. 10 illustrates an initial parameter calculation method in theinitial parameter calculation process as part of the operation of theedge extraction parameter generation unit included in the operatingdevice of the pattern inspecting device according to the firstembodiment.

FIG. 11 illustrates the meaning of edge extraction parameter values inthe pattern inspecting device according to the first embodiment.

FIG. 12 illustrates an example of a weighting function used in aninitial parameter smoothing process as part of the operation of the edgeextraction parameter generation unit included in the operating device ofthe pattern inspecting device according to the first embodiment.

FIGS. 13A-13C illustrate an example of an initial parameter and an edgeextraction parameter in the pattern inspecting device according to thefirst embodiment.

FIG. 14 is a flowchart of an operation of an inspection unit included inthe operating device of the pattern inspecting device according to thefirst embodiment.

FIGS. 15A-15C illustrate the operation of the inspection unit includedin the operating device of the pattern inspecting device according tothe first embodiment. FIG. 15(a) illustrates an initial state. FIG.15(b) illustrates a state in which defect candidates have been detectedusing a first defect determination threshold value. FIG. 15(c)illustrates a state in which the defect candidates have been expandedusing a second defect determination threshold value.

FIGS. 16A-16C illustrate the content of images output from the patterninspecting device according to the first embodiment. FIG. 16(a) shows animage of a drawing of a reference pattern; FIG. 16(b) shows aninspection image; FIG. 16(c) shows an image indicating informationconcerning a region detected as a defect; and FIG. 16(d) shows an imageindicating the extent of divergence of an edge extraction parameter ofeach local region from an average value.

FIG. 17 is a flowchart illustrating an operation concerning alength-measuring contour line repair process as part of the operation ofa contour line forming unit included in the operating device accordingto a first modification of the first embodiment.

FIGS. 18A-18C illustrate an operation concerning a masked thinningprocess in the length-measuring contour line repair process, as part ofthe operation of the contour line forming unit included in the operatingdevice according to the first modification of the first embodiment.

FIG. 19 is a flowchart illustrating an operation concerning, as part ofthe operation of the contour line forming unit included in the operatingdevice according to the first modification of the first embodiment, anintra-gap length-measuring contour line repair process in thelength-measuring contour line repair process.

FIG. 20 is a flowchart illustrating an operation concerning, as part ofthe operation of the contour line forming unit included in the operatingdevice according to the first modification of the first embodiment, aninter-gap length-measuring contour line repair process in thelength-measuring contour line repair process.

FIG. 21 illustrates, as part of the operation of the contour lineforming unit included in the operating device according to a firstmodification of the first embodiment, an operation of thelength-measuring contour line repair process.

FIGS. 22A and 22B illustrate, as part of the operation of the contourline forming unit included in the operating device according to thefirst modification of the first embodiment, an operation of theintra-gap length-measuring contour line repair process.

FIGS. 23A and 23B illustrate, as part of the operation of the contourline forming unit included in the operating device according to thefirst modification of the first embodiment, an operation of theintra-gap length-measuring contour line repair process.

FIGS. 24A and 24B illustrate, as part of the operation of the contourline forming unit included in the operating device according to thefirst modification of the first embodiment, an operation of theinter-gap length-measuring contour line repair process.

FIGS. 25A-25C illustrate, as part of the operation of the contour lineforming unit included in the operating device according to the firstmodification of the first embodiment, an operation of the inter-gaplength-measuring contour line repair process.

FIG. 26 illustrates a configuration of a dimension measuring deviceaccording to a second embodiment.

FIG. 27 is a flowchart of an operation of the dimension measuring deviceaccording to the second embodiment.

FIGS. 28A-28I illustrate an operation of the dimension measuring deviceaccording to the second embodiment.

FIGS. 29A and 29B illustrate an input interface for a process parameterset by the operator of the operation terminal 120 in the dimensionmeasuring device according to the second embodiment.

FIGS. 30A and 30B illustrate a measurement result presenting method inthe dimension measuring device according to the second embodiment.

FIG. 31 illustrates a configuration of the dimension measuring deviceaccording to a third embodiment.

FIG. 32 is a flowchart of an operation of the dimension measuring deviceaccording to the third embodiment.

FIGS. 33A-33G illustrate an operation of the dimension measuring deviceaccording to the third embodiment.

FIG. 34 illustrates a measurement result presenting method in thedimension measuring device according to the third embodiment.

FIG. 35 illustrates a configuration of the dimension measuring deviceaccording to a fourth embodiment.

FIG. 36 is a flowchart of an operation of a parameter calibration unitincluded in the operating device of the dimension measuring deviceaccording to the fourth embodiment.

FIGS. 37A-37C illustrate an operation of the parameter calibration unitincluded in the operating device of the dimension measuring deviceaccording to the fourth embodiment.

FIG. 38 is a flowchart of an operation of the dimension measuring deviceaccording to the fourth embodiment.

FIG. 39 illustrates a configuration of a pattern inspecting deviceaccording to a fifth embodiment.

FIG. 40 is a flowchart of an operation of the pattern inspecting deviceaccording to the fifth embodiment.

FIG. 41 illustrates an inspection object designating method in thepattern inspecting device according to the fifth embodiment.

FIGS. 42A-42C illustrate an inspection method in the pattern inspectingdevice according to the fifth embodiment.

FIGS. 43A and 43B illustrate, as part of the operation of the contourline forming unit included in the operating device according to thefirst modification of the first embodiment, a defect type distinguishingmethod in a case where the inter-gap length-measuring contour linerepair process is performed. FIG. 44(a) illustrates a state in whichbridging is caused. FIG. 44(b) illustrates a state in which necking iscaused.

FIGS. 44A-44E illustrate an inspection image acquisition method in thepattern inspecting device according to a second modification of thefirst embodiment. FIG. 44(a) illustrates a sample as the object ofinspection. FIG. 44(b) illustrates an inspection image acquisitionmethod in an inspection object range. FIG. 44(c) illustrates aconventional inspection image. FIG. 44(d) illustrates an inspectionimage in the second modification of the first embodiment. FIG. 44(e)illustrates an inspection image in a case where longitudinal and lateraldirections of a die are inclined relatively to the direction of movementof a stage.

FIG. 45 is a flowchart of an operation of the pattern inspecting deviceaccording to the second modification of the first embodiment.

DESCRIPTION OF EMBODIMENTS

In the examples described below, a description will be given mainly of apattern inspecting and measuring device for decreasing the influence ofnoise and the like and increasing the reliability of an inspection ormeasurement result during inspection or measurement using the positionof an edge extracted from image data obtained by imaging a pattern asthe object of inspection or measurement, and a computer program forcausing a computer to execute the above process.

In order to achieve the above purpose, in the examples described below,there will be described mainly a pattern inspecting and measuring devicein which inspection or measurement of an inspection or measurementobject pattern is performed using the position of an edge extracted,with the use of an edge extraction parameter, from image data obtainedby imaging an inspection or measurement object pattern, wherein the edgeextraction parameter is generated using a reference pattern having ashape as an inspection or measurement reference and the image data, anda computer pro gram.

First Example First Embodiment

In the following, a first embodiment will be described with reference toFIG. 1 to FIG. 16. The present embodiment is an example of a patterninspecting device which may be suitably used for extracting, byinspection involving image acquisition in a relatively large field ofview with respect to the dimension of a pattern as the object ofevaluation (image acquisition at low magnification ratio), a patternregion or a “defect region” (region with high risk of defectdevelopment) which is locally deformed with respect to a contour shapegiven in advance as an inspection reference.

As the semiconductor process rule evolves and increasingly finerpatterns are transferred on a wafer, there is a growing need forinspection using design data so as to detect systematic defect caused bymask design flaw and the like. This is because, in addition to adecrease in the margin for parameter setting for mask design ortransfer, making it easier for systematic defect to be caused, theimportance of measures against systematic defects is increasing becausethe problem of systematic defects, as opposed to random defects, can beefficiently addressed by identifying the cause and implementing animproving measure. In the case of systematic defect, a defect isgenerated similarly for all dies. Thus, the defect cannot be detected bythe conventional inspection involving comparison of dies, and can onlybe detected by inspection based on comparison with design data. From theinspection perspective too, there is a growing need for inspection oftwo-dimensional shapes as well as inspection of dimension as aone-dimensional feature. During such inspection, due to the inspectionusing a low magnification ratio image in addition to the trend towardfiner patterns, the dimension of defect to be detected on the image ison a decreasing trend, as mentioned above.

When a locally deformed pattern region is extracted as a defect regionby comparison with design data, it is necessary to separate theinfluence of pattern thickening or thinning due to variations in thefocal distance or the amount of exposure within the shot. According tothe technology disclosed in Patent Literature 1, such influence isseparated from the amount of local pattern deformation as the amount ofglobal pattern deformation, and defect inspection is performed using theamount of local pattern deformation. While this is effective inaddressing the problem, there is also the problem described above.

Furthermore, from the viewpoint of decreasing the evaluation time, theinspection may involve the use of an image acquired while the stage(sample base) is moved. In this case, due to various factors such as thenon-uniform speed of movement of the stage, the pattern shape on theimage obtained by imaging a pattern may be distorted with respect to theactual shape of the pattern on the wafer. While such distortion isnormally corrected before comparison with design data, residualdistortion may remain in the form of a sufficiently small deformationrelative to the dimension of the defect to be detected.

Based on the analysis described above, the present embodiment solves theproblem as will be described below.

[Configuration of Pattern Inspecting Device]

FIG. 1 illustrates a configuration of a pattern inspecting deviceaccording to the present embodiment, which is an example of a patterninspecting device in which an SEM is used as an imaging device. Thepattern inspecting device according to the present embodiment includesan imaging device 100 provided with an SEM 101 and an SEM control device102, an operating/processing device 110, an operation terminal 120, anda storage device 130.

The SEM 101 includes an electron gun 101 a, a condenser lens 101 b, adeflector 101 c, an ExB deflector 101 d, an objective lens 101 e, astage 101 h, and a secondary electron detector 101 k. A primary electronbeam emitted by the electron gun 101 a is converged by the condenserlens 101 b and irradiated via the deflector 101 c, the ExB deflector 101d, and the objective lens 101 e, forming a focal point on a sample(wafer) 101 g placed on the stage 101 h. As the electron beam isirradiated, secondary electrons are generated from the sample 101 g. Thesecondary electrons generated from the sample 101 g are deflected by theExB deflector 101 d, and then detected by the secondary electrondetector 101 k. The secondary electrons generated from the sample aredetected in synchronism with a two-dimensional scan of the electron beamby the deflector 101 c, or in synchronism with a repetitive operation ofthe electron beam in the X-direction by the deflector 101 c and withcontinuous movement of the sample 101 g in the Y-direction by the stage101 h. As a result, a two-dimensional electron beam image is obtained. Asignal detected by the secondary electron detector 101 k is converted byan A/D convertor 101 m into a digital signal which is then sent to theoperating/processing device 110 via the control device 102.

The control device 102 enables an electron beam scan under desiredconditions by controlling the SEM 101. The control device 102 supplies adeflecting signal to the deflector 101 c for setting a scan position ata desired position on the sample. In accordance with the suppliedsignal, the deflector 101 c changes a field of view dimension(magnification ratio) to a desired dimension. The control device 102sends to the operating/processing device 110 an inspection imageobtained by arranging detection signals obtained by the detector 101 kin synchronism with the scan by the deflector 101 c.

The configuration of the SEM 101 and the control device 102 is notlimited to the illustrated configuration and may include anyconfiguration such that an inspection image obtained by imaging thesample 101 g under desired conditions can be supplied to theoperating/processing device 110.

The operating/processing device 110 includes a memory 111; an initialsetting unit 112 that executes a process such as step S201 of FIG. 2; anedge extraction parameter generation unit 113 that executes a processsuch as step S202 of FIG. 2; a contour line forming unit 114 thatexecutes a process such as step S203 of FIG. 2; and an inspection unit115 that executes a process such as step S204 of FIG. 2. Theoperating/processing device 110 inspects a pattern formed on the sample101 g by comparing an inspection image input from the imaging device 100with a reference contour line formed from design data stored in thestorage device 130. Information necessary for the processes executed inthe operating/processing device 110 may be stored in the memory 111 inthe operating/processing device 110 as an inspection recipe. The recipeincludes an operating program for causing the pattern inspecting deviceto be automatically operated. The recipe may be stored in the memory 111or an external storage medium for each type of the sample as the objectof inspection, and is read as needed.

The operating/processing device 110 is connected to the operationterminal 120 which is provided with an input means such as a keyboard.The operating/processing device 110 has the function of receiving aninput from the operator via the input means, and displaying an image oran inspection result and the like to be presented to the operator on adisplay device provided in the operation terminal 120. These functionsmay be implemented using a graphical interface called graphical userinterface (GUI), for example.

Some or all of controls or processes in the operating/processing device110 may be implemented by allocating the controls or processes to anelectronic computer and the like provided with a CPU and a memorycapable of accumulating images. The operation terminal 120 alsofunctions as an imaging recipe creating device that creates, eithermanually or by using electronic device design data stored in the storagedevice 130, an imaging recipe which may include the coordinates of anelectronic device necessary for inspection, dictionary data (as will bedescribed later) for pattern matching utilized for positioning purpose,and photography conditions.

The storage device 130 stores the design data and the dictionary data,and may include a hard disk, for example. According to the presentembodiment, the design data refers to data for defining atwo-dimensional contour shape as an inspection evaluation reference, andis not limited to the electronic device design data per se. For example,the design data may include a layout pattern describing the layout of apattern figure to be formed on the wafer; a contour shape determined bya method such as lithography simulation from a mask pattern shape formedon the basis of the electronic device design data; or a contour shapeextracted from a non-defective pattern. In the present embodiment, asthe design data, a curve (which may include a broken line or a polygon)forming the outline of an exposure pattern obtained by a lithographysimulator is used. The design data is configured to include the numberof pattern figures; the coordinates of vertexes included in each patternfigure; and information about connection relationship of the vertexes,so that a polygon representing the contour shape as the evaluationreference can be defined. The connection relationship information isconfigured as orientation-attached information so that the inside andoutside of a pattern can be distinguished. Further, as will be describedbelow (FIG. 2), there is also stored dictionary data, which is geometricinformation concerning a region used as a template during positioning bythe initial setting unit 112 between the reference contour line and theinspection image, in association with a reference pattern. Thedictionary data includes, for example, coordinate information of thecenter position of a region and region dimension information.Specifically, information concerning one or more regions suitable as atemplate region that have been extracted in view of “uniqueness in asearch range”, for example, is generated and stored in advance. Byretaining the information of the template for positioning as dictionarydata rather than as image data, the amount of data to be retained can bereduced compared with a case where the information is retained as imagedata.

As needed, the configuration may include a simulator 140 that determinesthe pattern shape formed on the wafer on the basis of the design datastored in the storage device 130. In such configuration, when thedifference between the two-dimensional contour shape determined by thedesign data initially stored in the storage device 130 and the patternshape expected to be formed on the wafer is large, the pattern shapeexpected to be formed on the wafer can be determined by the simulator140 from the initially stored design data to obtain a reference patternas the inspection evaluation reference. Thus, false alert can bedecreased and inspection reliability can be increased.

[Operation of Pattern Inspecting Device]

An operation of the pattern inspecting device according to the presentembodiment will be described with reference to FIG. 2. FIG. 2 is aflowchart of the operation of the pattern inspecting device according tothe present embodiment.

As the pattern inspection process is started, initially, in step S201,the initial setting unit 112 performs initial setting of an inspectionimage and a reference pattern. Specifically, the process concerning theinitial setting of the inspection image and the reference pattern is asfollows.

First, the initial setting unit 112 reads an inspection image from theimaging device 100, and implements preprocessing as needed. Thepreprocessing includes, for example, a smoothing process for noiseremoval. The preprocessing may be suitably implemented using knowntechnology.

The initial setting unit 112 then reads the design data from the storagedevice 130 in a range corresponding to the inspection image, and, afterperforming a design data deforming process, such as a pattern figureedge rounding process as needed, determines a reference contour line onthe basis of the design data after deformation. The reading of thedesign data in the range corresponding to the inspection image includesreading all design data such that a part of the polygon representing thecontour shape as the evaluation reference could be included in the rangecorresponding to the inspection image (the range taking intoconsideration a margin corresponding to a position error at the time ofinspection image acquisition, for example), using the vertex coordinatesand connection relationship information in the design data. Namely, notjust the data such that, of the sides of the polygon, at least onevertex is included in the range corresponding to the inspection image,but also data such that a part of the sides intersects the rangecorresponding to the inspection image are read. The reference contourline is a connection of reference edges based on the design data, andprovides a reference pattern as the inspection reference in the presentembodiment. Of the operation of the initial setting unit 112, anoperation concerning a process of determining the reference contour lineon the basis of the design data (reference contour line forming process)will be described later (see FIG. 3).

The initial setting unit 112 further reads the dictionary data from thestorage device 130 in the range corresponding to the inspection image,and implements positioning of the reference contour line and theinspection image. The positioning of the reference contour line and theinspection image may be implemented using known technology. For example,template matching using a normalized cross-correlation value as anevaluation value may be used. In this case, the template image may beone obtained by, for example, determining a region suitable forpositioning with reference to the dictionary data, drawing a referencecontour line included in the region on an image, and then blurring thereference contour line using a smoothing filter, such as a Gaussianfilter. In another example of the method of positioning the referencecontour line and the inspection image, a reference contour line includedin the region suitable for positioning which is determined withreference to the dictionary data and a contour line extracted from theinspection image using a Sobel filter and the like may be positioned bya contour line matching technique. The contour line matching may beaccurately implemented by using a two-stage technique using generalizedHough transform for coarse search and an iterative closest point (ICP)algorithm for fine search. Alternatively, template matching using anormalized cross-correlation value as the evaluation value may beimplemented. In this case, a template image is obtained by drawing on animage the reference contour line which is determined with reference tothe dictionary data and included in the region suitable for positioning,and blurring the reference contour line using a smoothing filter such asa Gaussian filter, whereas a searched image is obtained by drawing acontour line extracted from the inspection image using a Sobel filterand the like on an image, and blurring the contour line using asmoothing filter such as a Gaussian filter. The method of positioning ofthe reference contour line and the inspection image is not limited tothe above, and the positioning may be implemented by various othermethods. When there is a plurality of “regions suitable for positioning”determined with reference to the dictionary data, one of the regions maybe used for positioning; a final positioning result may be determinedfrom the result of independent positioning in each region; or aplurality of regions may be combined for simultaneous positioning.

Then, in step S202, the edge extraction parameter generation unit 113generates an edge extraction parameter. Specifically, the process ofstep S202 includes determining one edge extraction parameter for eachreference edge, using the inspection image and the reference contourline that are in a positioned state. In the present embodiment, becausethe contour line forming unit 114 uses a threshold value method, the“threshold value” as a parameter used when extracting an edge by thethreshold value method provides the edge extraction parameter. The edgeextraction parameter is calculated such that the edge extracted from theinspection image in a normal portion and the reference edge aresubstantially aligned. The operation of the edge extraction parametergeneration unit 113 will be described later (see FIG. 6).

Thereafter, in step S203, the contour line forming unit 114, using theedge extraction parameter generated in step S202, extracts a lengthmeasuring edge (which will be described later), and forms alength-measuring contour line (which will be described later).Specifically, the process of step S203 is a process of determining, froma brightness profile generated for each reference edge, an edge used inthe process in the inspection unit 115 on the basis of the edgeextraction parameter corresponding to the reference edge. In thefollowing description, particularly the edge determined using thebrightness profile will be referred to as a “length measuring edge”. Inthe present example, because the value of an edge placement error (EPE,which corresponds to the distance from the reference edge to the lengthmeasuring edge in the present embodiment) is referenced in the processof the inspection unit 115 which will be described later, only thedistance from the reference edge to the length measuring edge isdetermined. However, depending on the purpose of inspection ormeasurement, the length measuring edge may be determined as a string oftwo-dimensional coordinates in the coordinate system of the inspectionimage, the coordinates may be linked in accordance with the way thereference edges are linked, and then handled as a contour line. Such alink of length measuring edges will be referred to as a“length-measuring contour line”. By handling as a contour line, ageometric smoothing process can be implemented using known technologysuch as curve approximation, whereby disturbance in the shape of thecontour line due to the influence of noise can be decreased. Further, bydefining, as needed, the way the EPE is measured not in terms of a“point-to-point” distance but in terms of a “point-to-polygon” or a“polygon-to-polygon” distance, the EPE measurement accuracy can also beincreased. Further, intersection of line segments intersecting eachother may be detected, and a process of deleting or moving the lengthmeasuring edges, or modifying the order of their arrangement may beimplemented so as to eliminate the intersection. By additionallyperforming such processes, when it is desired to grasp a shapedifference using the area of a disagreeing portion of the referencecontour line and the length-measuring contour line as an index, forexample, it becomes possible to increase the reliability of the index.In the following description of processes in the present specification,in view of such modifications, the length-measuring contour line isformed even when it is not necessarily required to form thelength-measuring contour line after extraction of a length measuringedge.

Thereafter, in step S204, the inspection unit 115 inspects the patternby comparing the length-measuring contour line formed by the contourline forming unit 114 and the reference contour line, outputsinformation concerning a region determined to be a defect region as aninspection result, and ends the pattern inspection process. Of theoperation of the inspection unit 115, the pattern inspection operationcomparing the length-measuring contour line and the reference contourline will be described later with reference to FIG. 14 and FIG. 15. Ofthe operation of the inspection unit 115, the operation concerning theoutput of the inspection result will be described later with referenceto FIG. 16.

[Operation Concerning Reference Contour Line Forming Process as Part ofOperation of Initial Setting Unit 112]

An operation concerning a reference contour line forming process as partof the operation of the initial setting unit 112 will be described withreference to FIG. 3 to FIG. 5.

FIG. 3 is a flowchart of an operation concerning a reference contourline forming process as part of the operation of the initial settingunit 112 included in the operating/processing device 110 according tothe present embodiment.

As the reference contour line forming process is started, in step S301,the initial setting unit 112 reads the design data from the storagedevice 130, and stores the number of pattern figures that have been readin a counter MJ.

In step S302, the initial setting unit 112 extracts reference edges. Thereference edges are extracted at maximum and regular intervals notexceeding a given maximum interval, for each pattern figure included inthe design data. The reference edge may be configured to be extractedsuch that the density is varied in accordance with curvature, namely,such that the density of portions with high curvature is higher than thedensity of portions with low curvature. In this case, the shape of aportion with high curvature can be better reflected in the extractedcontour. The details of the process of step S302 will be described later(see FIG. 5).

In step S303, the initial setting unit 112 selects the reference edges.This is a process of selecting, from among the reference edges extractedin step S302, only those reference edges that could be included in aninspection range, and registering successive reference edges as onesegment. In consideration of position error correction, the referenceedges included in a range wider than the imaging range of the inspectionimage (FOV) by a predetermined width are selected. In step S303, theinitial setting unit 112 increments the value of the counter MS that hasbeen initialized to “0” by “1” each time a segment is registered so asto make the counter MS value correspond to the number of segments thatare to be made the object of processing. Also, the number NS of thereference edges included in an S-th segment is stored in associationwith the segment.

The contents of the processes of step S302 and step S303 will bedescribed with reference to FIG. 4.

FIG. 4 illustrates, as part of the operation of the initial setting unit112 included in the operating/processing device 110 according to thepresent embodiment, a reference edge extraction method and a referenceedge selection method in the reference contour line forming process.

In FIG. 4, a rectangle 401 is the imaging range of the inspection image(FOV). A rectangle 402 corresponds to the rectangle 401 as enlarged,with respect to each of the upper-lower and left-right directions, bydistances corresponding to the sum of the maximum amount of positionerror and the maximum interval of the reference edges that could beassumed in view of the specifications.

A figure 410 is a pattern figure which is expressed as a polygon forminga directed cycle. Depending on whether on the right side or left side ofa directed side, the inside and outside of the pattern can bedistinguished. In the example of FIG. 4, the pattern is oriented inclockwise direction.

The reference edge 411 is a reference edge corresponding to a vertexthat is initially registered of the data of the FIG. 410. In the processof step S302, a reference edge group including reference edges 412 to415 is extracted at regular intervals from the reference edge 411 as thestart point and along the direction of the directed side.

In the process of step S303, with respect to each of the reference edgesincluded in the extracted reference edge group, it is determined whetherthe reference edge is included in the rectangle 402. Of the referenceedges determined to be included in the rectangle 402, a string ofsuccessive reference edges is registered as one segment. Specifically, astring of reference edges from the reference edge 412 to the referenceedge 413 is registered as one segment, and a string of reference edgesfrom the reference edge 414 to the reference edge 415 is registered asanother segment.

FIG. 5 is a flowchart illustrating an operation concerning the referenceedge extraction process (S302) in the reference contour line formingprocess as part of the operation of the initial setting unit 112included in the operating/processing device 110 according to the presentembodiment.

In step S501, the initial setting unit 112 sets the value of a counterJ, which is a counter for identifying the pattern figure as the objectof processing, to “0”.

In step S502, the initial setting unit 112 computes a perimeter LJ ofthe J-th pattern figure. The perimeter LJ of the pattern figure may becomputed using a known method.

In step S503, the initial setting unit 112 calculates a samplinginterval PJ and the number NJ of reference edges with respect to theJ-th pattern figure from the perimeter LJ and a given maximum samplinginterval P. Specifically, if LJ is divisible by P, the reference edgesare located at positions dividing the shortest path into (LJ/P) equalparts. In this case, PJ is equal to P, and NJ is (P/LJ+1) because bothends are included. If LJ is not divisible by P, PJ and NJ may becalculated similarly considering that the reference edges are located atpositions dividing the shortest path into (LJ/P+1) equal parts. In thepresent embodiment, the value of P is 0.5 pixel; however, the value of Pis not limited to the above.

In step S504, the initial setting unit 112 sets the value of the counterN, which is a counter for identifying the reference edge as the objectof processing, to “0”.

In step S505, the initial setting unit 112 calculates the coordinates ofthe N-th reference edge as the coordinates of a point at which thedistance from the start point is “PJ×N”, and registers the coordinatesas the N-th reference edge of the J-th pattern figure.

In step S506, the initial setting unit 112 determines whether theprocessing has been completed for a required number of reference edges,by comparing the counter N with the number NJ of the reference edges. Ifthe processing has been completed for the required number of referenceedges (step S506: YES), the initial setting unit 112 proceeds to theprocess of step S508. If there is a reference edge that has not beenprocessed (step S506: NO), the initial setting unit 112 proceeds to stepS507, increments the value of the counter N by “1”, and then proceeds tostep S505 to continue the processing.

In step S508, the initial setting unit 112 determines whether theprocessing has been completed for the required number of patternfigures, by comparing the counter J with the counter MJ indicating thenumber of the pattern figures that have been read. If the processing hasbeen completed for the required number of pattern figures (step S508:YES), the initial setting unit 112 ends the reference edge extractionprocess. If there is a pattern figure that has not been processed (stepS508: NO), the initial setting unit 112 proceeds to step S509,increments the value of the counter J by “1”, and then proceeds to stepS502 to continue the processing.

[Operation of the Edge Extraction Parameter Generation Unit 113 Includedin the Operating/Processing Device 110]

The operation of the edge extraction parameter generation unit 113 willbe described with reference to FIG. 6 to FIG. 13.

FIG. 6 is a flowchart of the operation of the edge extraction parametergeneration unit 113 included in the operating/processing device 110according to the present embodiment.

In step S601, the edge extraction parameter generation unit 113determines, for each reference edge, a direction for acquiring abrightness profile, and generates the brightness profile. The process ofstep S601 will be described later (see FIG. 7).

In step S602, the edge extraction parameter generation unit 113, usingthe inspection image and a reference contour line, performs an initialparameter calculation process. The process of step S602 will bedescribed later (see FIG. 9).

In step S603, the edge extraction parameter generation unit 113 performsan initial parameter smoothing process. The process of step S603 will bedescribed later (FIG. 13).

FIG. 7 is a flowchart illustrating an operation concerning a brightnessprofile generation process as part of the operation of the edgeextraction parameter generation unit 113 included in theoperating/processing device 110 according to the present embodiment.

In step S701, the edge extraction parameter generation unit 113 sets thevalue of the counter S, which is a counter for identifying a segment asthe object of processing, to “0”.

In step S702, the edge extraction parameter generation unit 113 sets thevalue of the counter N, which is the counter for identifying thereference edge as the object of processing, to “0”.

In step S703, the edge extraction parameter generation unit 113 computesa profile acquisition direction at the N-th reference edge of the S-thsegment. The process of step S703 will be described later (FIG. 8).

In step S704, the edge extraction parameter generation unit 113generates the brightness profile at the N-th reference edge of the S-thsegment.

In step S705, the edge extraction parameter generation unit 113determines whether the processing has been completed with respect to therequired number of reference edges, by comparing the counter N with thenumber NS of the reference edges. If the processing with respect to therequired number of reference edges has been completed (step S705: YES),the edge extraction parameter generation unit 113 proceeds to theprocess of step S707. If there is a reference edge that has not beenprocessed (step S705: NO), the edge extraction parameter generation unit113 proceeds to step S706, increments the value of the counter N by “1”,and then proceeds to step S703 to continue the processing.

In step S707, the edge extraction parameter generation unit 113determines whether the processing with respect to the required number ofsegments has been completed, by comparing the counter S with the counterMS indicating the number of segments. If the processing with respect tothe required number of segments has been completed (step S707: YES), theedge extraction parameter generation unit 113 ends the edge extractionparameter generation process. If there is a segment that has not beenprocessed (step S707: NO), the edge extraction parameter generation unit113 proceeds to step S708, increments the value of the counter S by “1”,and then proceeds to step S702 to continue the processing.

FIG. 8 illustrates a brightness profile acquisition direction in thebrightness profile generation process as part of the operation of theedge extraction parameter generation unit 113 included in theoperating/processing device 110 of the pattern inspecting deviceaccording to the present embodiment.

The brightness profile acquisition direction with respect to the N-threference edge 802 of interest is determined as a directionperpendicular to the direction of the tangent to a segment 800 at theposition of a reference edge 802. For example, the brightness profileacquisition direction is acquired using the coordinates of the referenceedge 801 which is the reference edge one edge prior to the referenceedge 802 on the segment 800, and the coordinates of the reference edge803 which is the reference edge one edge subsequent to the referenceedge 802 on the segment 800. When the coordinates of the reference edge801 are (X1, Y1), and the coordinates of the reference edge 803 are (X3,Y3), first, as a vector (TX, TY) obtained by normalizing a vector(X3−X1, Y3−Y1) to the length of one, a directional vector of the line810 corresponding to the tangent to the segment 800 at the referenceedge 802 is determined, and then a directional vector (DX, DY) of theline 820 which is a line perpendicular to the line 810 is determined as(−TY, TX). The brightness profile is generated as a one-dimensionalfunction on the line 820 using the origin of positional coordinates asthe position of the reference pattern 802. An interval 823 is a profileacquisition interval. In the present example, the profile acquisitioninterval 823 is from a point 821 spaced apart from the reference edge802 by a predetermined distance R on the negative side to a point 822spaced apart on the positive side by the predetermined distance R. Thebrightness profile is generated by sampling pixel values at sub-pixelintervals (such as at 0.5 pixel intervals) in the profile acquisitioninterval 823. The pixel value sampling may be performed using a knowntechnique, such as bilinear interpolation.

FIG. 9 is a flowchart illustrating an operation concerning an initialparameter calculation process as part of the operation of the edgeextraction parameter generation unit 113 included in theoperating/processing device 110 according to the present embodiment.

In step S901, the edge extraction parameter generation unit 113 sets thevalue of the counter S, which is the counter for identifying the segmentas the object of processing, to “0”.

In step S902, the edge extraction parameter generation unit 113 sets thevalue of the counter N, which is the counter for identifying thereference edge as the object of processing, to “0”.

In step S903, the edge extraction parameter generation unit 113determines an initial parameter calculation interval in the brightnessprofile concerning the N-th reference edge of the S-th segment. Theinitial parameter calculation interval may be determined as one thatincludes a reference edge from among a sum set of one interval that isupwardly convex and intervals on both sides thereof that are downwardlyconvex.

If no such interval is found, namely if the pixel values of the pixelsin the vicinity of the reference edge are so flat as to only havevariations of the order of a noise level, this means that there is noportion within the profile acquisition interval that is suitable as alength measuring edge. Thus, in order to make a defect candidatedetermination in the later-described process of step S1401, exceptionalvalues may be placed at both ends of the initial parameter calculationinterval so that no length measuring edge is associated with thereference edge. The flatness determination may be made using apredetermined threshold value designated by the recipe and the like, orusing a noise level separately estimated from the inspection image by aknown method. Other methods may also be used for the determination.

In step S904, the edge extraction parameter generation unit 113determines a positive-side minimum value, a negative-side minimum value,and a maximum value in the initial parameter calculation interval.

In step S905, the edge extraction parameter generation unit 113calculates an initial parameter in the N-th reference edge of the S-thsegment and registers the initial parameter.

In step S906, the edge extraction parameter generation unit 113determines whether the processing has been completed with respect to therequired number of reference edges by comparing the counter N with thenumber NS of the reference edges. If the processing has been completedwith respect to the required number of reference edges (step S906: YES),the edge extraction parameter generation unit 113 proceeds to theprocess of step S908. If there is a reference edge that has not beenprocessed (step S906: NO), the edge extraction parameter generation unit113 proceeds to step S907, increments the value of the counter N by “1”,and then proceeds to step S903 to continue the processing.

In step S908, the edge extraction parameter generation unit 113determines whether the processing has been completed with respect to therequired number of segments by comparing the counter S with the counterMS indicating the number of segments. If the processing has beencompleted with respect to the required number of segments (step S908:YES), the edge extraction parameter generation unit 113 ends the initialparameter calculation process. If there is a segment that has not beenprocessed (step S908: NO), the edge extraction parameter generation unit113 proceeds to step S909, increments the value of the counter S by “1”,and then proceeds to step S902 to continue the processing.

FIG. 10 illustrates an initial parameter calculation method in theinitial parameter calculation process as part of the operation of theedge extraction parameter generation unit 113 included in theoperating/processing device 110 of the pattern inspecting deviceaccording to the present embodiment.

The initial parameter is calculated using a position 1011, correspondingto a point 1001 at which a negative-side minimum value is achieved on abrightness profile 1000, within the profile acquisition interval; aposition 1012, corresponding to a point 1002 at which a positive-sideminimum value is achieved, within the profile acquisition interval; aposition 1013, corresponding to a point 1003 at which a maximum value isachieved, within the profile acquisition interval; and a negative-sideminimum value VBM, a positive-side minimum value VBP, and a maximumvalue VT. An interval 1020 is an interval providing the rangecorresponding to the edge extraction parameter domain [−1.0, 1.0] in theprofile acquisition interval. The pixel value at the position of thereference edge in the profile 1000 is the pixel value VC. An edgeextraction parameter corresponding to the pixel value VC provides theinitial parameter. Conversion of a pixel value to an edge extractionparameter is performed in accordance with a definition in FIG. 11.

FIG. 11 illustrates the meanings of edge extraction parameter values inthe present embodiment.

As opposed to the conventional threshold value method using only oneside of a brightness profile peak (which side with respect to the pointat which a maximum value is achieved is to be used may be designated bythe recipe and the like), according to the present embodiment, thebrightness profile utilizes both sides of the point 1003 at which themaximum value is achieved. Thus, as the threshold value domain, insteadof values such as [0%, 100%], but [−1.0, 1.0] including a negative valueis used as the domain. Further, in order to ensure continuity of valuesat the points on the brightness profile, the value of the edgeextraction parameter 1101 corresponding to the negative-side minimumvalue is “−1”; the value of the edge extraction parameter 1102corresponding to the maximum value is “±0”; and the value of the edgeextraction parameter 1103 corresponding to the positive-side minimumvalue is “+1”. The positive or negative sign is defined by a magnituderelationship with respect to the position 1013, corresponding to thepoint 1003 at which the maximum value is achieved, within the profileacquisition interval.

For example, the position of the edge corresponding to an edgeextraction parameter 1104 is a position 1114 which is the positioncorresponding to a point 1124 of intersection with the brightnessprofile 1000. The position of the edge corresponding to an edgeextraction parameter 1105 is a position 1115 which is the positioncorresponding to a point 1125 of intersection with the brightnessprofile 1000. These positions are defined as a one-dimensionalcoordinate system having the position 802 of the reference edge as theorigin. Thus, the positions provide an EPE value corresponding to therelevant reference edge as is. In the present example, because theprocess of the inspection unit 115 is only based on the EPE value, it isnot necessary to calculate a two-dimensional contour shape using thedirectional vector (DX, DY). However, when it is necessary to calculatea two-dimensional contour shape, coordinate conversion may be performedusing the directional vector (DX, DY) and the EPE value. At this time, aprocess for eliminating a self-crossing may be added as needed.

Conversion from the pixel value V to the edge extraction parameter maybe performed according to “(V−VT)/(VT−VBM)” when the position at whichthe pixel value V is achieved is smaller than the position 1013 at whichthe maximum value is achieved, or “(VT−V)/(VT−VBP)” when greater.

FIG. 12 illustrates an example of a weighting function used in aninitial parameter smoothing process as part of the operation of the edgeextraction parameter generation unit 113 included in theoperating/processing device 110 according to the present embodiment.

A curve 1201 is a smooth function defined such that the weight isincreased as the absolute value of Δp becomes smaller. Δp is a functionof the initial parameter. In the present example, the value of theinitial parameter per se is used, assuming that the ideal value of theinitial parameter is “0.0”. As a specific example of the curve 1201,“0.5+0.5×cos(π·|Δp|)” may be used. When the ideal value of the initialparameter is set other than “0.0”, the absolute value of Δp is set to benot greater than “1.0”, assuming that a difference from the ideal valuesmaller than “−1.0” is “−1.0” and that a difference from the ideal valuegreater than “1.0” is “1.0”. The function used as the curve 1201 is notlimited to the above example.

FIG. 13 illustrates an example of the initial parameter and the edgeextraction parameter in the present embodiment.

When a curve 1301 shown in FIG. 13(a) which is a drawing of thereference pattern and a curve 1302 shown in FIG. 13(b) which correspondsto the ridge of a white band are actually overlapping as shown in FIG.13(c), a parameter for extracting an edge at the position of the curve1301, namely the initial parameter, is like a curve 1312, for example.By weighted-averaging the curve 1312 using the weighting functionindicated by the curve 1201 of FIG. 12 and a predetermined dimensionwindow, a curve 1313 is obtained. The curve 1313 provides the edgeextraction parameter obtained as a result of the initial parametersmoothing process S603. In the process of the contour line forming unit114, namely the process of step S203, an edge is extracted for eachreference edge using the edge extraction parameter corresponding to thereference edge. Thus, in a normal portion, because the differencebetween the initial parameter and the parameter as a result of smoothingis small, an edge is extracted in the vicinity of the reference pattern.In a defect portion, because the difference between the initialparameter and the parameter as a result of smoothing is large, an edgeis extracted at a position spaced apart from the reference pattern. Withregard to the dimension of the window used for determining the curve1313, i.e., the edge extraction parameter, a value described in theinspection recipe, or a value input by the operator via an input meansof the operation terminal 120 may be used. When the window dimension isrelatively small, compared with a case where the window dimension isrelatively large, a length measuring edge is extracted at a positioncloser to the reference pattern. When the window dimension is relativelylarge, compared with the case where the window dimension is relativelysmall, a length measuring edge is extracted such that finerirregularities can be expressed. Thus, the window dimension may be setin view of the dimension of the defect to be detected.

For the window dimension used for determining the edge extractionparameter, different values may be used depending on the shape of thereference pattern. For example, separate values may be used between alinear portion and a corner portion. This is for lowering the defectdetection sensitivity for a corner portion by decreasing the windowdimension for the corner portion because it can be expected that, whenthe reference pattern is formed by rounding a corner of a layoutpattern, for example, the divergence of the corner portion will becomelarger.

[Operation of the Inspection Unit 115 Included in theOperating/Processing Device 110 of the Pattern Inspecting Device]

The operation of the inspection unit 115 will be described withreference to FIG. 14 to FIG. 16.

FIG. 14 is a flowchart of an operation of the inspection unit 115included in the operating/processing device 110 of the patterninspecting device according to the present embodiment. In the presentembodiment, the inspection unit 115 detects a portion with a large shapedeformation from the design data and outputs the portion as a defectregion.

As a defect determination process is started, initially, the inspectionunit 115 extracts, as defect candidates, reference edges with EPE of notless than a first threshold value in step S1401, and registers thedefect candidates in a defect candidate list. The first defectdetermination threshold value is a value corresponding to “an amount ofdivergence from the design data such that the risk of defect developmentis considered high”. As a specific value, a value described in theinspection recipe, or a value input from the operator via the inputmeans of the operation terminal 120 may be used. The “amount ofdivergence from the design data such that the risk of defect developmentis high” corresponds to a value which has conventionally been given as“tolerance”.

The defect candidate list is information about the intervals on thereference contour line that may possibly be finally output as a defectregion, and holds information about “from the Ns-th reference edge tothe Nt-th reference edge” of the S-th segment with respect to eachdefect candidate. The content of the defect candidate list is suitablyupdated by the inspection unit 115 in the process of step S1401 toS1403. Upon reaching the process of step S1404, the locationscorresponding to the intervals remaining in the defect candidate listare finally output as defect regions.

In the process of step S903, the EPE value at a reference edge which isnot associated with the length measuring edge for reasons such as, forexample, that the initial parameter calculation interval is not found istreated as being infinite.

Thereafter, the inspection unit 115 in step S1402 expands the defectcandidates to the reference edges such that the EPE is not less than asecond defect determination threshold value. The second defectdetermination threshold value is a value smaller than the first defectdetermination threshold value. As the second defect determinationthreshold value, a value described in the inspection recipe, or a valueinput from the operator via the input means of the operation terminal120 may be used. The inspection unit 115 updates the information aboutthe defect candidates corresponding to the defect candidate list (i.e.,expands the intervals). If a plurality of defect candidates forms acontinuous interval, the plurality of defect candidates are integratedas one interval and the integrated interval is added to the defectcandidate list after the plurality of defect candidates are eliminatedfrom the defect candidate list.

The process of step S1402 is a process for preventing an erroneousdetermination such as a defect region being divided by fineirregularities in the shape of the length-measuring contour line,resulting in a false alert in the subsequent determination using a thirddefect determination threshold value. The second defect determinationthreshold value may be determined by a statistical method, such asdetermining an average value and a standard deviation of EPE at a normalportion using a discriminant analysis method (Otsu's method), andperforming a calculation using such values.

In step S1403, the inspection unit 115 makes a false alert determinationwith respect to each of the defect candidates registered in the defectcandidate list. If a false alert, the defect candidate is eliminatedfrom the defect candidate list. Specifically, it is determined, usingthe third defect determination threshold value corresponding to thedimension of the defect to be detected, whether an extracted defectcandidate has a predetermined length on the reference contour line. Ifthe defect candidate is less than the predetermined length on thereference contour line, the candidate is eliminated as being a falsealert. As the “length”, the number of the reference edges is used, forexample.

In step S1404, the inspection unit 115 integrates the defect candidatesand creates defect information. Specifically, after those of theextracted defect candidates that are proximate on the image areintegrated as one defect region, the circumscribed rectangle of theintegrated defect region is determined. Then, the center position of thecircumscribed rectangle is registered as the position of defect, and thedimension of the circumscribed rectangle is registered as the dimensionof the defect. When it is not necessary to decrease the number of defectregions that are output, the process of integrating the defect regionsmay be omitted.

After the process of step S1404, the inspection unit 115 ends the defectdetermination process.

FIG. 15 intuitively illustrates the operation of the inspection unit 115included in the operating/processing device 110 of the patterninspecting device according to the present embodiment. In FIG. 15, FIG.15(a) illustrates an initial state of the defect determination process;FIG. 15(b) illustrates a state in which defect candidates have beendetected using the first defect determination threshold value; and FIG.15(c) illustrates a state in which the defect candidates have beenexpanded using the second defect determination threshold value.

The defect determination process is performed, starting from the initialstate of FIG. 15(a), by successively referencing the EPE value, which isthe distance between the reference edges (such as a reference edge 1501)on a reference contour line 1500 and the length measuring edges (such asa length measuring edge 1511) corresponding to the reference edges.

In the process of step S1401, the reference edges of which the EPE isnot less than the first threshold value are extracted as the defectcandidates. In the case of FIG. 15(b), the reference edges of which theEPE is not less than a first defect determination threshold value 1521,namely a reference edge 1502, a reference edge 1503, a reference edge1504, a reference edge 1505, and a reference edge 1506 are extracted asdefect candidates.

In the process of step S1402, the defect candidates are expanded toreference edges of which the EPE is not less than the second thresholdvalue. In the case of FIG. 15(c), the EPE of the reference edgesadjacent to the reference edge 1502, the reference edge 1503, thereference edge 1504, the reference edge 1505, and the reference edge1506, which are the reference edges extracted as the defect candidates,is successively referenced along a reference contour line 1500. Then,the defect candidates are expanded to but not including the referenceedges of which the EPE is smaller than a second defect determinationthreshold value 1522. The defect candidates obtained by such expansionare a defect candidate 1530 and a defect candidate 1531.

In the process of step S1403, the false alert determination is made withrespect to the defect candidate 1530 and the defect candidate 1531.According to the present embodiment, the false alert determination ismade by observing the length on the reference contour line. Thus, whenthe third defect determination threshold value is “5”, for example, thedefect candidate 1530 of which the length is “8” is not determined to bea false alert and is finally output as a defect. On the other hand, thedefect candidate 1531 of which the length is “3” is determined to be afalse alert and eliminated from the defect candidate list.

FIG. 16 illustrates the contents of an inspection result image outputfrom the pattern inspecting device according to the present embodiment.The inspection result image is generated by the inspection unit 115 onthe basis of defect information obtained as a result of the defectdetermination process described with reference to FIG. 14 to FIG. 15.The inspection result image is displayed on an image display device ofthe operation terminal 120 by the operating/processing device 110, forexample.

In the present embodiment, the reference contour line is drawn as animage shown in FIG. 16(a). When an inspection image is obtained as shownin FIG. 16(b), the inspection unit 115 generates an image shown in FIG.16(c) or FIG. 16(d) as the inspection result image. The inspection imageof FIG. 16(b) represents a situation in which patterns which are notnormal are included in the image. Namely, the situation is such that apattern FIG. 1601 is generally thinned, while a pattern FIG. 1602 partlyhas a degree of thickening that is detected as a defect.

FIG. 16(c) shows an image for confirmation of information concerning thedetected defect regions by the operator of the operation terminal 120.The inspection unit 115 generates the image by cutting out and drawingan inspection image of a region corresponding to the defect region in anupper-left region 1611 of the image; cutting out and drawing thereference pattern in a region corresponding to the defect region in anupper-right region 1612; drawing an image, in which the length-measuringcontour line in a region corresponding to the defect region and thereference pattern are superposed one upon the other, in a lower-rightregion 1613; and drawing a location 1622 specifically determined to be adefect in a lower-left region 1614. The defect location 1622 correspondsto the thick portion of the pattern FIG. 1602 in the inspection image ofFIG. 16(b). The drawing of the defect location 1622 may be implementedby, for example, paining over a region enclosed by the reference contourline included in the defect location, the length-measuring contour linecorresponding to the reference contour line, and lines connecting thecorresponding reference edge and a length measuring edge. However, themethod of drawing the defect location 1622 is not limited to the above,and may include, for example, a method involving a morphological filterafter contour lines related to the defect location are drawn.

FIG. 16(d) shows an image for confirmation by the operator of theoperation terminal 120 of the degree of divergence of the edgeextraction parameter at each local region from an average value. Theinspection unit 115 computes, with respect to each reference edge, theabsolute value of the difference between the edge extraction parametercorresponding to the reference edge and an edge extraction parameterreference value (such as the value of an average of the edge extractionparameters corresponding to the reference edges). When the calculatedvalue is relatively large, the reference edge is drawn relativelythickly or with relatively large pixel value. When the calculated valueis relatively small, the reference edge is drawn relatively thinly orwith relatively small pixel values. As a result, the image shown in FIG.16(d) is generated. In the image of FIG. 16(d) generated by such method,the portion corresponding to the generally thinned pattern FIG. 1601 inthe inspection image of FIG. 16(b) is represented in such a way as to bevisually recognized as a bold line portion 1631, and the thick portionof the pattern FIG. 1602 in the inspection image of FIG. 16(b) as a boldline portion 1632. Thus, the image can be used, for example, forobserving variations in exposure conditions in a shot and making ananalysis that “the pattern shape around this portion of the die tends tobecome unstable”, or for checking the presence or absence of abnormalityin a scanner. Instead of the edge extraction parameter, the initialparameter (i.e., the initial value of the edge extraction parameter) maybe used to generate an image similar to FIG. 16(d). The edge extractionparameter itself may be used as one evaluation index for making thedefect region determination, whereby a portion with a different edgeextraction parameter from others can be determined as a defect regionand output as such.

Thus, by focusing on the edge extraction parameter to generate an image,it becomes possible to extract a pattern location at which the risk ofdefect development is expected to be relatively high compared to otherpattern regions, from a different point of view from the defectdetermination by dimension evaluation between patterns.

As described above, according to the first embodiment of the presentinvention, the edge extraction parameter for extracting an edge from theinspection image is generated, using the inspection image and thereference contour line, such that the edge of a normal portion isextracted in the vicinity of the reference contour line, and the edgedetermined from the inspection image on the basis of the generated edgeextraction parameter and the reference edge are compared for inspection.In this configuration, the influence of noise and the like can bedecreased, and the reliability of the inspection result can beincreased. Particularly, during inspection, the influence of globalshape deformation due to variations in the focal distance or the amountof exposure in the shot in which the inspected pattern was manufacturedcan be decreased. Thus, the configuration may be preferably used for thepurpose of mask defect search.

A configuration may be adopted where a range designating unit forinputting a range of values considered appropriate as the values of theedge extraction parameters generated by the edge extraction parametergeneration unit 104 is provided, so that the operator of the operationterminal 120 can designate the range of the edge extraction parametervalues. The configuration can prevent the phenomenon where a portionwhich should be detected as a defect fails to be detected and producesan erroneous alert due to edge extraction using an edge extractionparameter generated beyond a range determined to be appropriate as anadjustable range of the edge extraction parameter. The range of valuesconsidered appropriate as the edge extraction parameter values generatedby the edge extraction parameter generation unit 104 may be designatedby the inspection recipe.

In the foregoing embodiment, the edge extraction parameter is determinedfrom the initial parameter by a method using a weighted average.However, the method of determining the edge extraction parameter fromthe initial parameter is not limited to the above, and other techniquessuch as curve approximation may be used for the determination.

While in the foregoing embodiment the value “0.0” has been determined asan ideal value of Δp, the embodiment of the present invention is notlimited to the above. For example, an average value of the initialparameters for each pattern figure or inspection image may be determinedas being an ideal value.

In the foregoing embodiment, one edge extraction parameter is determinedfor each reference edge. However, the embodiment of the presentinvention is not limited to the above. For example, one edge extractionparameter may be determined in pattern figure units. Specifically, forexample, an average value of the initial parameters of reference edgesbelonging to a pattern figure may be used as the edge extractionparameter, or a search may be conducted for an edge extraction parametersuch that the length-measuring contour line best fits with respect tothe reference contour line. By adopting such configuration, thephenomenon of the length measuring edge being fitted to the referenceedge excessively can be prevented. Similarly, when the exposureconditions are assumed to be constant within the inspection image, oneedge extraction parameter may be determined for the inspection image asa whole.

The method of comparing the length-measuring contour line and thereference contour line, and the mode of output and the outputdestination of the inspection result are not limited to thoseillustrated by way of example with reference to FIG. 14 to FIG. 16 andin corresponding descriptions, and may be variously modified dependingon the purpose. For example, the mode of output of the inspection resultmay include, for visual confirmation, image information other than thosein the illustrated examples, or, for analysis and the like, informationsuch as the coordinates or dimension of the defect region, type ofdefect, and determination reliability. Alternatively, both may be outputassociated with each other. The output destination of the inspectionresult is not limited to the operation terminal 120 and may include anexternal storage device, or the inspection result may be transmitted viaa network to another system.

The present embodiment may also be applied for comparison of patternshapes between different steps, such as between pattern shapes after thelithography step and after the etching step. For example, inspection maybe performed using common design data between the different steps.Alternatively, using a contour line formed from one as a referencecontour line, the other may be inspected. In the case of pattern shapecomparison between different steps, the profile shapes are generallydifferent from each other. Thus, by employing the process using an edgeextraction parameter adaptively determined from the inspection image, asaccording to the present invention, the reliability of the inspectionresult can be increased compared with when a given edge extractionparameter is used. When applied for pattern shape comparison betweendifferent steps, “the influence of small roughness can be prevented”when the contour line formed from the one is used as the referencecontour line for inspecting the other. In view of this point being onefeature of the present embodiment, it is preferable to use the contourline with relatively small roughness as the reference contour line.Accordingly, it is preferable to evaluate the pattern shape of theresist after the lithography step using the pattern shape after theetching step as the reference contour line. When it is expected thatthere will be a design difference between the pattern shapes indifferent steps, the reference contour line may be expanded orcontracted by the expected amount of difference prior to processing. Inthis way, the reliability of the inspection result can be furtherincreased.

First Modification of the First Embodiment

In the following, a first modification of the first embodiment will bedescribed with reference to FIG. 17 to FIG. 25 and FIG. 43. The presentmodification is an example which is particularly preferable where, whenthe divergence from the reference pattern is large and the initialparameter calculation interval cannot be found in the process of stepS903, it is desired to more accurately grasp the shape of the defectlocation or, when bridging or necking is caused, it is desired to notjust detect such region as a defect region but also distinguish the typeof defect, such as “bridging” or “necking”. The pattern inspectingdevice of the present modification differs from the pattern inspectingdevice of the first embodiment mainly in the operation of the contourline forming unit 114. Specifically, in the present modification, thecontour line forming unit 114 forms the length-measuring contour linefor defect detection using the edge extraction parameter generated bythe edge extraction parameter generation process, and then implements alength-measuring contour line repair process. In the following, thelength-measuring contour line repair process will be described indetail.

FIG. 17 is a flowchart illustrating an operation concerning thelength-measuring contour line repair process as part of the operation ofthe contour line forming unit 114 included in the operating/processingdevice according to the modification of the present embodiment.

As the length-measuring contour line repair process is started, thecontour line forming unit 114 in step S1701 forms a first image contourline using the edge extraction parameter (namely, “0.0”) correspondingto a profile peak position. The image contour line is a contour linewhich is formed by linking bright portions on the image, and whichcorresponds to a ridge (ridge line) when pixel values are viewed asheight. In the present embodiment, the contour line is managed as acontour image (namely, an image such that the pixel values of the pixelsforming the image contour line are “1 (foreground)”, and the pixelvalues of other pixels are “0 (background)”) in pixel units. When thecoordinates at sub-pixel accuracy are required, coordinate values aredetermined by interpolation computation as the need arises.Alternatively, a contour line having a sub-pixel coordinate accuracy maybe generated in advance using a known method (such as Patent Literature1), and the contour line may be managed as geometric information in aknown data structure. The first image contour line is formed byextracting an edge for each reference edge having a corresponding lengthmeasuring edge, using an edge extraction parameter corresponding to theprofile peak position. When image edges (which, in the presentembodiment, refer to the pixels constituting the image contour line;however, when the contour line is configured to be managed as geometricinformation, the image edges may mean the positions of sub-pixelaccuracy edges) respectively corresponding to mutually adjacentreference edges do not correspond to the identical pixels or mutuallyadjacent pixels on the contour image, the gaps of the pixels areinterpolated by a straight line, for example, so as to maintainconnectivity.

In step S1702, the contour line forming unit 114 forms an image contourline candidate region by binarizing the inspection image. Specifically,the image contour line candidate region is provided by a set of pixelsthat belong to a class with greater pixel values upon binarization ofthe inspection image. The process of forming the image contour linecandidate region may be implemented by a known method. For example, theinspection image may be binarized based on a threshold value determinedby a known threshold value determination method, such as a discriminantanalysis method (Otsu's method). Alternatively, the inspection image maybe binarized by determining a different threshold value for each partialregion of the inspection image using a dynamic threshold value process.Further alternatively, the information about the first image contourline may be used during the threshold value determination.

In step S1703, the contour line forming unit 114 forms a second imagecontour line from the image contour line candidate region and the firstimage contour line by a masked thinning process. Specifically, in thecoordinate system of the inspection image, the image contour linecandidate region and the first image contour line are drawn in asuperposed manner, and then thinning is performed while the position ofthe first image contour line is maintained. Then, of the pixels on theresultant thin line, a set of pixels that are not included in the firstimage contour line provides the second image contour line. The detailsof the masked thinning process will be described later (see FIG. 18).

Then, in step S1704, the contour line forming unit 114 determines twopoints on the first image contour line that correspond to the ends of agap interval on the basis of the reference contour line. Specifically,the reference edges on the reference contour line that are retained as adirected graph are tracked in order. Then, a first image edgecorresponding to a reference edge satisfying a condition that “there isa first image edge corresponding to itself but there is no first imageedge corresponding to the reference edge next to itself” is determinedas a “gap interval start point”. A first image edge corresponding to areference edge satisfying a condition that “there is a first image edgecorresponding to itself but there is no first image edge correspondingto the reference edge in front of itself” is determined as a “gapinterval end point”. The “gap interval start point” and the “gapinterval end point” thus determined are registered in combination in agap interval list. Specifically, information indicating “from the Ns-threference edge to the Nt-th reference edge of the S-th segment” may beregistered. The gap interval list is referenced in the intra-gaplength-measuring contour line repair process of step S1705 and theinter-gap length-measuring contour line repair process of step S1706.Depending on the field of view (FOV) at the time of acquisition of theinspection image, there may be only one of the gap interval start pointor the end point. In such a case, when registering in the gap intervallist, if there is no start point, an exceptional value is stored in astart point side identifier Ns. If there is no end point, an exceptionalvalue is stored in an end point side identifier Nt. The registration inthe gap interval list is made even if there is only one of the startpoint or end point of the gap region because of possible use in theinter-gap length-measuring contour line repair process of step S1706.The number of the gap intervals registered in the gap interval list isreferenced in the intra-gap length-measuring contour line repair processof step S1705 and the inter-gap length-measuring contour line repairprocess of step S1706. Thus, a counter KT retaining the number of thegap intervals is initialized to “0” at the start of the length-measuringcontour line repair process, and then the value of the counter KT isincremented by “1” upon registration of a gap interval in the gapinterval list and counted in the process of step S1704.

After the process of step S1704, the contour line forming unit 114 instep S1705 performs the intra-gap length-measuring contour line repairprocess as will be described later with reference to FIG. 19. Further,in step S1706, the contour line forming unit 114 performs the inter-gaplength-measuring contour line repair process as will be described laterwith reference to the FIG. 20, and ends the length-measuring contourline repair process.

FIG. 18 illustrates an operation concerning a masked thinning process inthe length-measuring contour line repair process as part of theoperation of the contour line forming unit included in theoperating/processing device according to the modification of the presentembodiment.

FIG. 18(a) illustrates a state in which the first image contour line isdrawn, where the painted-over pixels correspond to the pixelsconstituting the first image contour line. FIG. 18(b) illustrates theimage contour line candidate regions having been drawn in a superposedmanner in addition to the first image contour line, where the pixelsdrawn with bold lines correspond to the pixels constituting the imagecontour line candidate regions. FIG. 18(c) illustrates the result of themasked thinning process, where the pixels drawn with bold lines andpainted over correspond to the pixels constituting the second imagecontour line. Thus, the masked thinning process is a process performedfor determining the second image contour line linked to the first imagecontour line while the position of the first image contour line ismaintained.

The method for creation of FIG. 18(b) to FIG. 18(c) may employ a knowntechnique. In the present embodiment, for example, Hilditch's thinningalgorithm is used. In this case, pixels as the object of update (i.e.,the pixels that may possibly be changed from the foreground to thebackground by the thinning process) are registered in a list in theorder of rastering (from upper left to lower right) in advance. Then, anodd-numbered iterative process is performed from top to bottom of thelist, while an even-numbered iterative process is performed from bottomto top of the list, so that a bold lined region is shaved into a thinline from different directions. At this time, convergence determinationis implemented each time the even-numbered process of the combination ofthe odd-numbered iterative process and the even-numbered iterativeprocess is completed. By not registering the pixels constituting thefirst image contour line in the list of the pixels as the object ofupdate, thinning can be performed while the position of the first imagecontour line is maintained.

If the first image contour line includes a closed chain and the entiretyof the inside of the closed chain forms an image contour line candidateregion, the image contour line candidate region is not thinned and left.In this regard, in order to achieve the purpose of the length-measuringcontour line repair process of the present embodiment, the followingprocess may be implemented. Namely, in the state of FIG. 18(c), thepixels constituting the first image contour line are removed, and thepixels constituting the second image contour line are separated intolink components. Of the link components thus obtained, those required bythe length-measuring contour line repair process are only those linkcomponents linking two or more end points in the first image contourline. Thus, the pixels constituting the link components that cannot linkthe two or more end points in the first image contour line are deletedfrom the second image contour line. Herein, the end points in the firstimage contour line refer to the pixels constituting the first imagecontour line that are each adjacent to only one of the pixelsconstituting the first image contour line.

FIG. 19 is a flowchart illustrating an operation concerning an intra-gaplength-measuring contour line repair process in the length-measuringcontour line repair process as part of the operation of the contour lineforming unit included in the operating/processing device according tothe modification of the present embodiment. The intra-gaplength-measuring contour line repair process is a process performedwhen, although a gap interval is produced for reasons such as that “theinitial parameter calculation interval cannot be found in the process ofstep S903 because the position of the length measuring edge to bedetermined is greatly diverged from the reference edge”, the lengthmeasuring edge can be determined in association with the reference edgeby properly setting the interval for brightness profile acquisition.This is a process for repairing the length-measuring contour line byrepeating a process of determining the interval for brightness profileacquisition using the image contour line with reference to eachreference edge in the gap interval, and then determining the lengthmeasuring edge using an interpolated edge extraction parameter. Theintra-gap length-measuring contour line repair process will beintuitively described later with reference to FIG. 21 to FIG. 23.

As the intra-gap length-measuring contour line repair process isstarted, in step S1901, the contour line forming unit 114 initially setsthe value of the counter K for identifying the gap interval as theobject of processing to “0”.

In step S1902, the contour line forming unit 114 determines the shortestpath connecting an image edge corresponding to the start point of theK-th gap interval and an image edge corresponding to the end point ofthe K-th gap interval on the second image contour line. Specifically,using the image edge corresponding to the start point of the K-th gapinterval, the image edge corresponding to the end point of the K-th gapinterval, and each of the second image edges as vertexes, the imageedges that are adjacent in eight pixels on the contour image areconnected by sides, a weighted undirected graph having the distancebetween pixel centers as the weight of the side is created, and theshortest path is determined by a known technique, such as the Dijkstra'smethod.

In the gap interval list, if an exceptional value is registered as theidentifier of the K-th gap interval start point or end point, it isdetermined that “the shortest path has not been found”, and the stepproceeds to the process of step S1903 without performing the shortestpath determination process.

In step S1903, the contour line forming unit 114 determines whether, asa result of the process of step S1902, the shortest path has been found.If the shortest path has been found (step S1903: YES), the contour lineforming unit 114 proceeds to the process of step S1904 and starts arepair process for the K-th gap interval. If the shortest path has notbeen found (step S1903: NO), the contour line forming unit 114 proceedsto the process of step S1908 assuming that the repair process for theK-th gap interval has been completed.

In step S1904, the contour line forming unit 114 sets the value of thecounter N for identifying the reference edge as the object of processingto “0”. The reference edge as the object of processing is such that thereference edge subsequent to the K-th gap interval start pointcorresponds to “N=0”. Subsequently, the reference edge is successivelyassociated with the value of N as the value is incremented one by oneuntil the reference edge in front of the K-th gap interval end point isreached.

In step S1905, the contour line forming unit 114 determines, withrespect to the N-th reference edge included in the K-th gap interval,the corresponding point on the shortest path. The corresponding point onthe shortest path may be determined, after a direction perpendicular tothe direction of the tangent to the reference contour line at theposition of the N-th reference edge of interest is determined similarlyto FIG. 8, as a point of intersection of a line extending from the N-threference edge of interest in the perpendicular direction and the imagecontour line at a portion corresponding to the shortest path.

In step S1906, the contour line forming unit 114 creates a brightnessprofile in an interval including the corresponding point on the shortestpath with respect to the N-th reference edge included in the K-th gapinterval, and determines a length measuring edge using an interpolatededge extraction parameter. The interpolation of the edge extractionparameter is implemented by linear interpolation using the edgeextraction parameter corresponding to the reference edge correspondingto the K-th gap interval start point, and the edge extraction parametercorresponding to the reference edge corresponding to the K-th gapinterval end point. Alternatively, the interpolation may be implementedby techniques other than linear interpolation, such as one using ahigher-order interpolation formula by increasing the number of thereference edges that are referenced.

In step S1907, the contour line forming unit 114 determines whether thelength measuring edge calculation has been completed with respect to allof reference edges included in the K-th gap interval, by comparing thevalue of the counter N and the number of the reference edges included inthe K-th gap interval. The number of the reference edges included in theK-th gap interval may be computed from the K-th gap interval start pointidentifier and end point identifier. When the length measuring edgecalculation has been completed for all of the reference edges includedin the K-th gap interval (step S1907: YES), the contour line formingunit 114, assuming that the repair process for the K-th gap interval hasbeen completed, marks the K-th gap interval as “repaired”, and proceedsto the process of step S1908. If there is a reference edge for which thelength measuring edge calculation is not completed (step S1907: NO), thecontour line forming unit 114 proceeds to step S1909 and increments thevalue of the counter N by “1”, and then proceeds to step S1905 tocontinue the repair process for the K-th gap interval.

In step S1908, the contour line forming unit 114 determines whether therepair process has been completed for all gap intervals by comparing thevalue of the counter K and the number KT of gap intervals. If the repairprocess has been completed with respect to all gap intervals (stepS1908: YES), the contour line forming unit 114 ends the intra-gaplength-measuring contour line repair process. If there is a gap intervalfor which the repair process has not been completed (step S1908: NO),the contour line forming unit 114 proceeds to step S1910 to incrementthe value of the counter K by “1” and then proceeds to step S1902 tocontinue the processing.

FIG. 20 is a flowchart illustrating an operation concerning theinter-gap length-measuring contour line repair process in thelength-measuring contour line repair process as part of the operation ofthe contour line forming unit included in the operating/processingdevice according to the modification of the present embodiment. Theinter-gap length-measuring contour line repair process is a process thatbecomes necessary when the length measuring edge cannot be determined inassociation with the reference edge, such as when in a necking orbridging state. The process repairs the length-measuring contour line byrepeating a process of determining the length measuring edge from thebrightness profile created in association with an image edge using aninterpolated edge extraction parameter. With regard to a gap intervalthat was not repaired at the start of the inter-gap length-measuringcontour line repair process, there is a necking or bridging state ifrepaired at the end of the inter-gap length-measuring contour linerepair process; if not repaired at the end of the inter-gaplength-measuring contour line repair process, there is a state in whichthe white band is lost by pattern crumbling and the like. Thus, the typeof defect can be distinguished. The necking state and the bridging statemay be distinguished by whether the repair portion of thelength-measuring contour line is positioned on the left or right side ofthe reference contour line of the gap portion. The inter-gaplength-measuring contour line repair process will be intuitivelydescribed later with reference to FIG. 21, FIG. 24, FIG. 25, and FIG.43.

As the inter-gap length-measuring contour line repair process isstarted, the contour line forming unit 114 in step S2001 initially setsthe value of the counter K for identifying the gap interval as theobject of processing to “0”.

Then, in step S2002, the contour line forming unit 114 determineswhether the K-th gap interval has been repaired. The determination ofwhether the K-th gap interval has been repaired may be made depending onwhether the K-th gap interval is marked as “repaired”. The method ofdetermination is not limited to the above. For example, thedetermination may be based on whether a length measuring edge isassociated with the reference edge in the K-th gap interval. If the K-thgap interval has been repaired (step S2002: YES), the contour lineforming unit 114, assuming that the repair process concerning the K-thgap interval has been completed, proceeds to the process of step S2009.If the K-th gap interval has not been repaired (step S2002: NO), thecontour line forming unit 114 proceeds to the process of step S2003.

In step S2003, the contour line forming unit 114 determines the shortestpath connecting the image edge corresponding to the start point of theK-th gap interval and the image edge corresponding to the end point ofanother gap interval on the second image contour line. Specifically, theshortest path may be determined using the image edge corresponding tothe start point of the K-th gap interval, the image edges correspondingto the end points of all of the other gap intervals that are notrepaired, and each of second image edges as vertexes, connecting theimage edges that are adjacent to each other in eight pixels on thecontour image by sides, creating a weighted undirected graph having thedistance between pixel centers as the weight of the side, and then usinga known technique such as the Dijkstra's method.

Thereafter, in step S2004, the contour line forming unit 114 determineswhether the shortest path has been found. If the shortest path has beenfound (step S2004: YES), the contour line forming unit 114 proceeds tothe process of step S2005 and starts a repair process concerning theK-th gap interval. If the shortest path has not been found (step S2004:NO), the contour line forming unit 114, assuming that the repair processconcerning the K-th gap interval has been completed, proceeds to theprocess of step S2009. Herein, “the repair process concerning the K-thgap interval” refers to a process for determining a length-measuringcontour line connecting the K-th gap interval start point and the endpoint of the other gap interval.

If the shortest path has been found, the contour line forming unit 114in step S2005 divides the shortest path by a plurality of repairingedges. The process of dividing the shortest path by the plurality ofrepairing edges is similar to the reference edge extraction processdescribed in step S302 and with reference to FIG. 5. Namely, the lengthLK of the shortest path is determined, and, based on the given maximumsampling interval P, the sampling interval PK and the number NK of therepairing edges with respect to the shortest path are calculated.Specifically, when LK is divisible by P, the repairing edges are locatedat positions dividing the shortest path into (LK/P) equal parts. In thiscase, PK is equal to P, and NK is (P/LK−1) because both ends areremoved. If LK is not divisible by P, PK and NK may be similarlydetermined in consideration of the fact that the repairing edges arelocated at positions dividing the shortest path into (LK/P+1) equalparts.

In step S2006, the contour line forming unit 114 sets the value of thecounter N for identifying the repairing edge as the object of processingto “0”.

In step S2007, the contour line forming unit 114 creates a brightnessprofile with respect to the N-th repairing edge included in the K-th gapinterval, and determines the length measuring edge using an interpolatededge extraction parameter. In the inter-gap length-measuring contourline repair process, there is no reference contour line at the portioncorresponding to the gap interval. Thus, the brightness profile iscreated using a repairing edge instead of the reference edge, and,instead of creating the brightness profile in a direction perpendicularto the reference contour line, the brightness profile is created in adirection perpendicular to the image contour line. Interpolation of theedge extraction parameter is implemented by linear interpolation using,as in the process of step S1906, an edge extraction parametercorresponding to the reference edge corresponding to the K-th gapinterval start point, and an edge extraction parameter corresponding tothe reference edge corresponding to the K-th gap interval end point. Theinterpolation may be implemented using techniques other than linearinterpolation, such as using a higher-order interpolation formula byincreasing the number of the reference edges that are referenced, as instep S1906.

In step S2008, the contour line forming unit 114 determines whether thelength measuring edge calculation has been completed with respect to allrepairing edges, by comparing the value of the counter N and the numberNK of the repairing edges. If the length measuring edge calculation hasbeen completed for all repairing edges (step S2008: YES), the contourline forming unit 114, assuming that the repair process concerning theK-th gap interval has been completed, marks the K-th gap interval as“repaired”, and proceeds to the process of step S2009. If there is arepairing edge for which the length measuring edge calculation has notbeen completed (step S2008: NO), the contour line forming unit 114proceeds to step S2010 and increments the value of the counter N by “1”,and then proceeds to step S2007 to continue the repair processconcerning the K-th gap interval.

In step S2009, the contour line forming unit 114 determines whether therepair process concerning all gap intervals has been completed, bycomparing the value of the counter K and the number KT of gap intervals.If the repair process concerning all gap intervals has been completed(step S2009: YES), the contour line forming unit 114 ends the inter-gaplength-measuring contour line repair process. If there is a gap intervalfor which the repair that has not been processed (step S2009: NO), thecontour line forming unit 114 proceeds to step S2011 to increment thevalue of the counter K by “1”, and then proceeds to step S2002 tocontinue the processing.

[Intuitive Description of Length-Measuring Contour Line Repair Process]

In the following, a process flow of the length-measuring contour linerepair process described with reference to FIG. 17 to FIG. 20 will bedescribed more intuitively with reference to FIG. 21 to FIG. 25 and FIG.43. In FIG. 21 to FIG. 25 and FIG. 43, similar signs designate similarelements.

FIG. 21 illustrates a state in which the process of step S1701 has beencompleted in the length-measuring contour line repair process describedwith reference to FIG. 17. A first image contour line 2120 and a firstimage contour line 2121 are formed in association with the respectiveintervals of a reference contour line 2100 of which a length-measuringcontour line 2110 and a length-measuring contour line 2111 have beendetermined. A first image contour line 2150 and a first image contourline 2151 are formed in association with respective intervals of areference contour line 2130 of which a length-measuring contour line2140 and a length-measuring contour line 2141 have been determined. Inthe state of FIG. 21, of the three continuous reference edges on thereference contour line 2100, i.e., a reference edge 2102, a referenceedge 2103, and a reference edge 2104, the reference edge 2103 does nothave a corresponding length measuring edge. Thus, the interval from thereference edge 2102 to the reference edge 2104 is a “gap interval”,providing the object of repair of the length-measuring contour line.Similarly, the reference edge 2133 does not have a corresponding lengthmeasuring edge, so that the interval from a reference edge 2132 to areference edge 2134 is a “gap interval”, providing the object of repairof the length-measuring contour line.

For the repair of the length-measuring contour line, priority is givento correspondence with the reference contour line. However, there may becases where it is inappropriate to perform the repair in such a way thatcorrespondence with the reference contour line can be achieved, such aswhen there is bridging or necking. Accordingly, in the presentmodification, after a repair is attempted by the intra-gaplength-measuring contour line repair process in such a way thatcorrespondence with the reference contour line can be achieved, the gapinterval that could not be repaired in such a way that correspondencewith the reference contour line can be achieved is subjected to a repairfor the case where correspondence with the reference contour line cannotbe achieved by the inter-gap length-measuring contour line repairprocess.

In the state of FIG. 21, when the length-measuring contour line isrepaired by the intra-gap length-measuring contour line repair process(S1705), the behavior will be such that a length measuring edge is addedbetween the length measuring edge 2112 and the length measuring edge2114 to connect the length-measuring contour line 2110 and thelength-measuring contour line 2111, forming one length-measuring contourline, or such that a length measuring edge is added between the lengthmeasuring edge 2142 and the length measuring edge 2144 to connect thelength-measuring contour line 2140 and the length-measuring contour line2141, forming one length-measuring contour line. This is the case for anexample which will be described later with reference to FIG. 22 and FIG.23.

In the state of FIG. 21, when the length-measuring contour line isrepaired by the inter-gap length-measuring contour line repair process(S1706), the behavior is such that a length measuring edge is addedbetween the length measuring edge 2112 and the length measuring edge2144 to connect the length-measuring contour line 2110 and thelength-measuring contour line 2141, forming one length-measuring contourline, or such that a length measuring edge is added between the lengthmeasuring edge 2142 and the length measuring edge 2114 to connect thelength-measuring contour line 2140 and the length-measuring contour line2111, forming one length-measuring contour line. This is the case for anexample which will be described later with reference to FIG. 24 and FIG.25.

FIG. 22 illustrates an example in which correspondence between thesecond image contour line formed in step S1703 and the reference contourline can be achieved. In the case of the example of FIG. 22, initially,in step S1703, a second image contour line 2220 and a second imagecontour line 2250 are formed. Then, in step S1704, two points on thefirst image contour line corresponding to both ends of the gap interval,i.e., a start point 2122 and an end point 2124, and a start point 2152and an end point 2154, are determined. In step S1902, the shortest pathconnecting the start point 2122 and the end point 2124, i.e., a secondimage contour line 2220, and the shortest path connecting the startpoint 2152 and the end point 2154, i.e., a second image contour line2250, are determined (see FIG. 22(a)). In step S1905, a search isconducted from the reference edge 2103 in a profile acquisitiondirection at the reference edge 2103 so as to determine a correspondingpoint 2223 on the shortest path. Further, a search is conducted from thereference edge 2133 in a profile acquisition direction at the referenceedge 2133 so as to determine a corresponding point 2253 on the shortestpath. In step S1906, based on the profile acquisition direction at thereference edge 2103, a brightness profile is created in a rangeincluding the corresponding point 2223 of the reference edge 2103, and alength measuring edge 2213 is determined using an edge extractionparameter interpolated from an edge extraction parameter at thereference edge 2102 and an edge extraction parameter at the referenceedge 2104. Similarly, a length measuring edge 2243 corresponding to thereference edge 2133 is also determined (see FIG. 22(b)).

FIG. 23 illustrates an example in which, while a plurality of differentinterpretations are possible, an interpretation can be made such thatcorrespondence between the second image contour line formed in stepS1703 and the reference contour line can be achieved. In the case of theexample of FIG. 23, initially, in step S1703, a second image contourline 2320 and a second image contour line 2350 are formed. However, atthe point in time of step S1703, the second image contour line 2320 andthe second image contour line 2350 are not formed as being separate, butthey are formed as one linked region having “X” shape. Then, in stepS1704, two points on the first image contour line corresponding to bothends of the gap interval, i.e., a start point 2122 and an end point2124, and a start point 2152 and an end point 2154 are determined. Then,in step S1902, the shortest path connecting the start point 2122 and theend point 2124, i.e., a second image contour line 2220, and the shortestpath connecting the start point 2152 and the end point 2154, i.e., asecond image contour line 2250 are determined. Namely, the image contourlines formed as one linked region having “X” shape at the point in timeof step S1703 are recognized as the two image contour lines of thesecond image contour line 2220 and the second image contour line 2250 atthe end of the process of step S1902 (see FIG. 23(a)). Thereafter, instep S1905, a search is conducted from the reference edge 2103 in theprofile acquisition direction at the reference edge 2103 so as todetermine a corresponding point 2323 on the shortest path. Also, asearch is conducted from the reference edge 2133 in the profileacquisition direction at the reference edge 2133 so as to determine acorresponding point 2353 on the shortest path. Herein, FIG. 23(b)illustrates the example in which the corresponding point 2353 is at thesame position as the corresponding point 2323. Then, in step S1906,based on the profile acquisition direction at the reference edge 2103, abrightness profile is created in a range including the correspondingpoint 2323 of the reference edge 2103, and a length measuring edge 2313is determined using an edge extraction parameter interpolated from anedge extraction parameter at the reference edge 2102 and an edgeextraction parameter at the reference edge 2104. Similarly, a lengthmeasuring edge 2343 corresponding to the reference edge 2133 is alsodetermined (see FIG. 23(b)).

FIG. 24 illustrates a first example in which correspondence between thesecond image contour line formed in step S1703 and the reference contourline cannot be achieved. In the case of the example of FIG. 24,initially, in step S1703, a second image contour line 2420 and a secondimage contour line 2450 are formed. Then, in step S1704, the two pointson the first image contour line corresponding to both ends of the gapinterval, i.e., the start point 2122 and the end point 2124, and thestart point 2152 and the end point 2154 are determined. In step S1902,it is attempted to determine the shortest path connecting the startpoint 2122 and the end point 2124, and the shortest path connecting thestart point 2152 and the end point 2154. However, this is unsuccessful.Thus, in step S2003, the shortest path connecting the start point 2122with any of the end points, and the shortest path connecting the startpoint 2152 with any of the end points are determined. In the case ofFIG. 24, as such shortest paths, a second image contour line 2420 and asecond image contour line 2450 are determined (see FIG. 24(a)). Then, instep S2005, the shortest path connected to the start point 2122, i.e.,the second image contour line 2420, is divided to obtain a repairingedge 2421 and a repairing edge 2422. Similarly, the shortest pathconnected to the start point 2152, i.e., the second image contour line2450, is divided to obtain a repairing edge 2451 and a repairing edge2452. In step S2007, using the normal direction to the second imagecontour line 2420 at the repairing edge 2421 as a profile acquisitiondirection, a brightness profile at the position of the repairing edge2421 is created, and a length measuring edge 2411 is determined using anedge extraction parameter interpolated from an edge extraction parameterat the reference edge 2102 and an edge extraction parameter at thereference edge 2134. Similarly, a length measuring edge 2412corresponding to the repairing edge 2422, a length measuring edge 2441corresponding to the repairing edge 2451, and a length measuring edge2442 corresponding to the repairing edge 2452 are determined (see FIG.24(b)).

FIG. 25 illustrates a second example in which correspondence between thesecond image contour line formed in step S1703 and the reference contourline cannot be achieved.

FIG. 25(a) illustrates a state in which the process of step S1701 hasbeen completed in the length-measuring contour line repair processdescribed with reference to FIG. 17. A first image contour line 2520 anda first image contour line 2521 are formed in association withrespective intervals of the reference contour line 2500 for which alength-measuring contour line 2510 and a length-measuring contour line2511 are respectively determined. A first image contour line 2550 and afirst image contour line 2551 are formed in association with respectiveintervals of the reference contour line 2530 for which alength-measuring contour line 2540 and a length-measuring contour line2541 are respectively determined. In the state of FIG. 25, of the threesuccessive reference edges on the reference contour line 2500, i.e., areference edge 2502, a reference edge 2503, and a reference edge 2504,the reference edge 2503 does not have a corresponding length measuringedge. Thus, the interval from the reference edge 2502 to the referenceedge 2504 provides a “gap interval”, which is the object of repair ofthe length-measuring contour line. Similarly, because the reference edge2533 does not have a corresponding length measuring edge, the intervalfrom the reference edge 2532 to the reference edge 2534 provides a “gapinterval”, which is the object of repair of the length-measuring contourline.

In the case of the example of FIG. 25, initially, in step S1703, asecond image contour line 2529 and a second image contour line 2559 areformed. Then, in step S1704, two points on the first image contour linecorresponding to both ends of the gap interval, i.e., a start point 2522and an end point 2524 and a start point 2552 and an end point 2554 aredetermined. Then, in step S1902, it is attempted to determine theshortest path connecting the start point 2522 and the end point 2524,and the shortest path connecting the start point 2552 and the end point2554. However, the attempt is unsuccessful, so that in step S2003 theshortest path connecting the start point 2522 with any of the endpoints, and the shortest path connecting the start point 2552 with anyof the end points are determined. In the case of the example of FIG. 25,as such shortest paths, the second image contour line 2529 and thesecond image contour line 2559 are determined (see FIG. 25(b)).Thereafter, in step S2005, the shortest path connected to the startpoint 2522, i.e., the second image contour line 2529 is divided toobtain a repairing edge 2525 and a repairing edge 2526. Similarly, theshortest path connected to the start point 2552, i.e., the second imagecontour line 2559 is divided to obtain a repairing edge 2555 and arepairing edge 2556. Then, in step S2007, using the normal direction tothe second image contour line 2529 at the position of the repairing edge2525 as a profile acquisition direction, a brightness profile at theposition of the repairing edge 2525 is created, and a length measuringedge 2515 is determined using an edge extraction parameter determined byinterpolation from an edge extraction parameter at the reference edge2502 and an edge extraction parameter at the reference edge 2534.Similarly, a length measuring edge 2516 corresponding to the repairingedge 2526, a length measuring edge 2545 corresponding to the repairingedge 2555, and a length measuring edge 2546 corresponding to therepairing edge 2556 are determined (see FIG. 25(c)).

FIG. 43 illustrates a method of distinguishing whether the state ofdefect is bridging or necking when a repair is conducted in theinter-gap length-measuring contour line repair process. In FIG. 43,portions similar to those of FIG. 24 are designated with signs similarto those of FIG. 24, and their detailed description will be omitted.Further, in FIG. 43, portions similar to those of FIG. 25 are designatedwith signs similar to those of FIG. 25, and their detailed descriptionwill be omitted.

FIG. 43(a) illustrates an example of bridging corresponding to the caseof FIG. 24. FIG. 43(b) illustrates an example of necking correspondingto the case of FIG. 25. In FIG. 43(a), with respect to an image 4310 inwhich reference contour lines are drawn, an image 4311 is provided withhatching on the side where a pattern is present, with reference toinformation about the orientation of the reference contour line. Bycomparing these images with an image 4320 in which length-measuringcontour lines are drawn, it can be seen that the portion of thelength-measuring contour lines that is related to the inter-gaplength-measuring contour line repair process, i.e., the interval fromthe length measuring edge 2112 to the length measuring edge 2144, forexample, is present on the left side of the reference contour lineincluding the reference edge 2102 and the reference edge 2104. This canbe determined by various methods. For example, the image 4311 iscreated, and the length of the shortest path (first shortest path) fromthe reference edge 2102 corresponding to the length measuring edge 2112to the reference edge 2134 corresponding to the length measuring edge2144 through the region without hatching is compared with the length ofthe shortest path (second shortest path) through the region withhatching. Then, if the length of the first shortest path is shorter, itis determined that there is “bridging”; if the length of the secondshortest path is shorter, it is determined that there is “necking”. Ifthere is no shortest path, the shortest path length is defined as“infinite”. The first shortest path may be determined by knowntechnology, such as Dijkstra's method, using the pixels of the image4311 as vertexes, and linking the vertexes corresponding to the pixelsthat are adjacent in the region without hatching by sides, the weight ofthe sides being the distance between the pixels. The second shortestpath may also be determined by a similar method with the exception thatthe vertexes corresponding to the pixels that are adjacent in the regionwith hatching are connected by sides. From the vertexes corresponding tothe pixels corresponding to the reference edge 2102 and the referenceedge 2134, the sides are connected to the vertexes corresponding to eachof adjacent pixels.

In the case of FIG. 43(b) too, with respect to an image 4330 in whichreference contour lines are drawn, an image 4331 is provided withhatching on the side where a pattern is present with reference toinformation about the orientation of the reference contour lines. As inthe case of FIG. 43(a), by comparing these images and an image 4340 inwhich length-measuring contour lines are drawn, it can be determinedthat there is a necking state.

Thus, the present modification is provided with the process of repairingthe length-measuring contour line in the interval in which thelength-measuring contour line is lacking when a contour line for defectdetection is formed. In this way, when the amount of deformation fromthe reference pattern is large and the initial parameter calculationinterval cannot be found in the process of step S903, the shape of thedefect location can be more accurately grasped. Further, when there isbridging or necking, not only the region can be detected as a defectregion but also the type of defect such as “bridging” or “necking” canbe distinguished. The result of the distinguishing may be output asinformation accompanying the defect information.

In the process of step S1902 of the intra-gap length-measuring contourline repair process described with reference to FIG. 19, and in theprocess of step S2003 of the inter-gap length-measuring contour linerepair process described with reference to FIG. 20, when the weightedundirected graph is created for the shortest path determination, aprocess of separating the second image edge into link components on thecontour image may be added as preprocessing. By adding suchpreprocessing, when the weighted undirected graph is created in theprocess of step S1902 or step S2003, only the second image edgesincluded in the link component adjacent to the start point of the gapinterval of interest may be considered the object of processing, ratherthan the second image edges as a whole, whereby the processing time canbe decreased.

The weighted undirected graph may also be created such that the weightof the side is “0”, and the weight of the vertex has a positive valuethat decreases with increasing pixel value. In this case, instead ofdetermining the shortest path, a path with the minimum weight isdetermined. The minimum weight path may be determined by a knowntechnique. In this configuration, the contour line may be repaired usinga path that preferentially traces portions that appear brightly on theinspection image.

Second Modification of the First Embodiment

In the following, a second modification of the first embodiment will bedescribed with reference to FIG. 44 and FIG. 45. The presentmodification represents an example of a pattern inspecting device whichmay be preferably used for inspecting a wide range on a wafer as theobject of inspection at high speed while preventing the phenomenon of anedge parallel with the electron beam scan direction being blurred by theinfluence of charge. The pattern inspecting device according to thepresent modification differs from the pattern inspecting deviceaccording to the first embodiment mainly in the inspection imageacquisition method and the process flow of the pattern inspectionprocess. Thus, in the following, the inspection image acquisition methodand the process flow of the pattern inspection process will be describedin detail.

FIG. 44 illustrates an inspection image acquisition method in thepattern inspecting device according to the present modification. In thepresent modification, a wide range of a semiconductor pattern formed ona die 4401 on a wafer 4400 shown in FIG. 44(a) is considered the objectof inspection. In order to acquire an SEM image of the range of theinspection object at high speed, an SEM image is acquired while thestage (sample base) is moved. For example, when the inspection objectrange is as shown by an inspection range 4402 in FIG. 44(b), SEM imagesare acquired successively along the directions of arrows whileoverlapping boundary portions of a first inspection stripe (band-likeinspection range) 4410, a second inspection stripe 4411, a thirdinspection stripe 4412, and so on (namely, the stage is moved in theopposite directions to the arrows). FIG. 44(b) illustrates a state inwhich the third inspection stripe 4412 is still being acquired. Fromeach inspection stripe, longitudinal image data are acquired. Theacquired image data are input to the operating/processing device 110 asan inspection image for a pattern inspection process. Conventionally,when the inspection image is acquired, an electron beam scan isperformed in a direction perpendicular to the direction of movement ofthe stage. Thus, for example in an inspection image 4420 shown in FIG.44(c), a phenomenon may be caused in which a lateral pattern 4430parallel with the electron beam scan direction is blurred by theinfluence of charge. Because a semiconductor circuit pattern generallyoften includes longitudinal and lateral patterns, some measure againstthe phenomenon has been sought. In this respect, according to thepresent modification, the electron beam scan direction is inclined withrespect to the direction perpendicular to the direction of movement ofthe stage (hereafter referred to as “inclined scan”). As a result, animage such as an inspection image 4421 shown in FIG. 44(d) is acquired.By adopting such configuration, the electron beam scan direction and thedirection of the lateral pattern 4430 do not become parallel, wherebythe degree of blurring of the lateral pattern 4430 by the influence ofcharge can be decreased. The angle of inclination of the electron beamscan direction with respect to the direction perpendicular to thedirection of movement of the stage (hereafter referred to as an“inclined scan angle”) is 10 degrees in the present modification.However, the angle is not limited to the above. Instead of inclining theelectron beam scan direction with respect to the direction perpendicularto the direction of movement of the stage, the die may be inclinedrelatively to the direction of movement of the stage. In this way, asillustrated by an inspection image 4422 shown in FIG. 44(e), theelectron beam scan direction and the direction of the lateral pattern4430 do not become parallel, whereby the phenomenon of the lateralpattern 4430 being blurred by the influence of charge can be solved.However, in this case, the number of the inspection stripes required forinspecting the entire surface of the die increases, and the processbecomes complex due to different dimensions of the inspection images foreach inspection stripe (for example, the algorithm for increasingprocessor allocation efficiency in a parallelized process becomescomplex). Thus, there still remains a problem from the viewpoint of highspeed inspection, as opposed to the method according to the presentmodification. Further, in the method of the present modification,respective longitudinal patterns included in the same inspection stripeare inspected under the same conditions, so that the reliability of theinspection result can be said to be high compared with the method ofFIG. 44(e) by which the longitudinal patterns are included in aplurality of inspection stripes. In FIG. 44(c), FIG. 44(d), and FIG.44(e), white bands are drawn with black lines from the viewpoint ofvisibility.

FIG. 45 is a flowchart of an operation of the pattern inspecting deviceaccording to the present modification. In FIG. 45, portions similar tothose of FIG. 2 are designated with similar signs in FIG. 2 and theirdetailed description will be omitted.

As the pattern inspection process is started, initially, in step S4501,the initial setting unit 112 performs initial setting of an inspectionimage and a reference pattern. Preprocessing concerning the inspectionimage is a process similar to that of step S201. With regard to designdata, the design data of a range corresponding to the inspection imageis read from the storage device 130. After a design data deformingprocess, such as a pattern figure edge rounding process, is performed asneeded, conversion to an oblique coordinate system is performed based onthe inclined scan angle, and then a reference contour line is determinedbased on the converted design data. With regard to the positioning ofthe reference contour line and the inspection image, the rangeidentified by the inclined scan using dictionary data is aparallelogram. Thus, in order not to detract from the uniqueness of thedictionary data, after the parallelogram is determined based on theinclined scan angle, a template image corresponding to a rectangularregion that circumscribes the parallelogram is generated, and templatematching is performed.

As a method for handling the inclined scan, the inspection image may besubjected to coordinate conversion instead of the design data. However,since one of the features of the present invention lies in the use of alength measuring edge determined by generating an appropriate edgeextraction parameter so as to perform sub-pixel accuracy inspection.Accordingly, it is preferable to use a design data converting methodthat does not affect the brightness profile.

The processes of step S202 and step S203 that are performed after theprocess of step S4501 are similar to the processes according to thefirst embodiment. After the process of step S203, in step S4504, theinspection unit 115 inspects the pattern by comparing thelength-measuring contour line formed in step S203 with the referencecontour line. After information concerning a region determined to be adefect region is output as an inspection result, the pattern inspectionprocess is completed. The process of step S4504 differs from the processof step S204 in that at the start of the process, with respect to thelength-measuring contour line and the reference contour line, conversionfrom the oblique coordinate system to the orthogonal coordinate systemis implemented based on the inclined scan angle. Because these contourlines provide geometric information, no degradation of information iscaused by the coordinate system conversion process. Further, theorthogonal coordinate system conversion enables defect determinationbased on correct distance. The process after the implementation of thecoordinate system conversion process with respect to thelength-measuring contour line and the reference contour line is similarto the process of step S204.

Thus, according to the present modification, with respect also to theinspection image obtained by imaging involving stage movement andinclined scan, the present invention is applied using the configurationwith reduced influence on the brightness profile. Thus, the reliabilityof the inspection result can be increased.

In the present modification, the SEM image is acquired while the stageis moved. However, the method of acquiring the SEM image according tothe present invention is not limited to the above configuration, andvarious other methods for inspecting the band-like regions may be used.For example, an SEM image is acquired after the stage is stopped, andthe stage is moved to the next inspection position after the SEM imageacquisition has been completed. In this case, the electron beam scandirection may be inclined with respect to a direction perpendicular tothe longitudinal direction of the band-like region.

Second Example Second Embodiment

In the following, a second embodiment will be described with referenceto FIG. 26 to FIG. 30. The present embodiment represents an example of adimension measuring device which may be preferably used for measuringthe dimension of the evaluation object pattern while decreasing theinfluence of noise or the influence of small roughness.

In the field of semiconductor manufacturing, dimension management hasbeen implemented using a dimension measured from an image obtained byCD-SEM (SEM image), by a threshold value method, for example. The objectof dimension management includes, for example, the line pattern widthand hole pattern diameter. As the process rule evolves, patterndimension becomes smaller, and the influence of length measurement valuevariations accompanying side wall irregularities on the patterndimension becomes relatively large. As a result, there is a growing needfor accurately measuring and managing an index referred to as line edgeroughness (LER) or line width roughness (LWR). For example, the LER orLWR is measured by dividing a predetermined measurement range atmultiple points in a longitudinal direction from a line pattern imageobtained by CD-SEM, and determining the variation (3σ) of the amount ofdivergence from an edge position reference line determined in eachdivided range by a technique such as a threshold value method, or thevariation (3σ) of the length measurement value. However, it is knownthat if noise is superposed on the acquired image, an error called“noise-induced bias” is caused by a displacement of the position of anobservation edge from a true position due to image noise at the time ofextracting the pattern edge, and it is desirable to decrease the error.

When a fixed edge extraction parameter is used, irregularities arecaused in the contour line used for length measurement due to theinfluence of noise and the like. In the method by which the contour lineis geometrically smoothed in order to decrease the contour lineirregularities, even an irregular shape that is desired to be reflectedin the measurement value could possibly be smoothed. According to theinventor's analysis, one reason for this is smoothing withoutconsideration of the profile shape. Further, by the method that uses anaveraged brightness profile for decreasing the variations, a portionwith a different side wall shape is also included in the averagingcalculation. As a result, even if a processing technique of aligning thepeak positions of the brightness profile is implemented during theaveraging process, for example, the greater the range that is averaged,the less visible will the local feature that should be picked up become.

The inventor, based on the understanding that the above problem iscaused by the determination of the edge position using the same edgeextraction parameter in all brightness profiles, proposes the presentembodiment as a solution example. In the present embodiment, a contourline formed with a predetermined edge extraction parameter described bythe recipe and the like is used as a reference contour line, an edgeextraction parameter suitable for measuring dimension is generated, anda contour line for measuring dimension is formed. Hereafter, the detailswill be described.

FIG. 26 illustrates a configuration of a dimension measuring deviceaccording to the present embodiment. In FIG. 26, portions similar tothose of FIG. 1 are designated with similar signs in FIG. 1, and theirdetailed description will be omitted.

An operating/processing device 2610 according to the present embodimentincludes the memory 111; an initial setting unit 2611 that executes theprocess of step S2701 and the like of FIG. 27; a reference contour lineforming unit 2612 that executes the process of step S2702 and the likeof FIG. 27; an edge extraction parameter generation unit 2613 thatexecutes the process of step S2703 to S2708 and the like of FIG. 27; adimension measuring contour line forming unit 2614 that executes theprocess of step S2709 and the like of FIG. 27; and a pattern dimensionmeasurement unit 2615 that executes the process of step S2710 and thelike of FIG. 27. Based on an SEM image input from the imaging device100, the dimension of the pattern formed on the sample 101 g ismeasured. Information required for processes executed by theoperating/processing device 2610, such as “how the dimension of whichportion of the pattern present at which position on the sample is to bemeasured”, is stored in the memory 111 in the operating/processingdevice 2610 as a dimension measuring recipe. The recipe includes anoperating program for automatically operating the dimension measuringdevice. The recipe may be stored in the memory 111 or an externalstorage medium for each type of the sample as the object of measurement,and is read as needed.

The operating/processing device 2610 is also connected to the operationterminal 120. In response to an input from the operator via the inputmeans of the operation terminal 120, the operating/processing device2610 modifies the content of the measurement process or displays ameasurement result and the like on a display device of the operationterminal 120 as needed. These functions may be implemented by agraphical interface called “GUI”, for example.

An operation of the dimension measuring device according to the presentembodiment will be described with reference to FIG. 27 to FIG. 30. FIG.27 is a flowchart of the operation of the dimension measuring deviceaccording to the present embodiment. FIG. 28 illustrates chartsgenerated by a simulation assuming the measurement of the line width oflongitudinal line patterns for describing the operation of the dimensionmeasuring device according to the present embodiment. Specifically, theedge position in FIG. 28 indicates the edge position on one side ofcontour lines formed in length measuring cursors on both left and rightsides when the length measuring cursors 3001 (as will be describedlater) are disposed with respect to a longitudinal line pattern as shownin FIG. 30(a). Thus, in FIG. 28, each curve is expressed as a functionof the Y-coordinate (longitudinal position). An interval 2801 isintended for behavior observation when there is an exceptional value orthe influence of noise. An interval 2802 is an interval intended forobservation of a behavior with respect to a gradual and large changealso accompanied by a change, such as a defect, in the shape of abrightness profile.

The method of dimension measurement according to the present embodimentis similar to conventional dimension measuring method with the exceptionthat, as the edge extraction parameter for generating thelength-measuring contour line for dimension measurement, a valuegenerated by the operating/processing device 2610 is used. Namely, asshown in FIG. 30(a), a range as the object of measurement is designatedusing the length measuring cursor 3001, and length measuring edges aredetermined at predetermined intervals in the measurement object range.Then, dimension measurement is performed using a plurality of thedetermined length measuring edges. Whether the brightness profile iscreated toward the inside or outside of the disposed length measuringcursor 3001 is designated by the dimension measuring recipe and the likestored in the memory 111 in the operating/processing device 2610. Theedge extraction parameter for determining the length measuring edgeswill be described with reference to an example of using the thresholdvalue method. Thus, the edge extraction parameter takes a value of notlower than “0%” and not more than “100%”.

As the dimension measurement process is started, initially, in stepS2701, the initial setting unit 2611 performs initial setting of an SEMimage as the object of processing. Specifically, the initial settingunit 2611 initially acquires the SEM image from the imaging device 100,and implements preprocessing as needed. The preprocessing includes, forexample, a smoothing process for noise removal. The preprocessing may besuitably implemented using a known technology. In the followingdescription of the present embodiment, the SEM image that has beensubjected to preprocessing as needed may be simply referred to as “SEMimage”. The initial setting unit 2611 then, based on the dimensionmeasuring recipe stored in the memory 111 of the operating/processingdevice 2610, locates the length measuring cursor at a predeterminedposition of the SEM image. If a field of view error could be caused whenthe SEM image is acquired, it is necessary to perform positioncorrection when locating the length measuring cursor. The amount ofcorrection may be determined by known technology. For example, when, asinformation for positioning, image data of a non-defective portion isregistered in the recipe together with reference coordinates, thedetermination may be made by template matching using a normalizedcross-correlation value and the like as an evaluation value. When, aspositioning information, design data of a layout pattern and the like isregistered in the recipe together with reference coordinates, thedetermination may be made by matching of a contour line extracted fromthe image data and the design data.

Then, in step S2702, the reference contour line forming unit 2612determines from the SEM image a reference contour line using apredetermined edge extraction parameter P0 (see FIG. 28(a)). For thepredetermined edge extraction parameter P0, a value designated by adimension measuring recipe stored in the memory 111 and the like of theoperating/processing device 2610, or a value input from the operator viathe input means of the operation terminal 120 is used. When the valueinput by the operator is used, a mode of GUI as will be described latermay be used (see FIG. 29). The reference contour line in the presentembodiment is a contour line as a dimension measurement reference, andformed by successively determining length measuring edges correspondingto the predetermined edge extraction parameter P0 using knowntechnology, such as a threshold value method. In this case, the positionand direction for acquiring the brightness profile are determined by thedimension measurement method and the location of the length measuringcursor which may be designated by the dimension measuring recipe. Forexample, FIG. 30(a) illustrates an example in which the line width of alongitudinal line pattern is measured. The reference edges are set atpredetermined intervals in the length measuring cursor, and thedirection in which the brightness profile is acquired is the lateraldirection, i.e., a direction parallel to an X-axis.

The position and direction of brightness profile acquisition may bedetermined based on the image contour line. For example, after an imagecontour line is determined from the SEM image using known technology,edges are disposed at regular intervals along the image contour line,and a brightness profile is acquired at the position of the edges in adirection perpendicular to the direction of the tangent to the imagecontour line. In this configuration, the present embodiment can beapplied even when the length measuring cursor is not disposed, such aswhen two-dimensional shape evaluation is desired, for example.

In step S2703, the edge extraction parameter generation unit 2613smoothes the reference contour line to determine a smoothed referencecontour line (see FIG. 28(b)). Specifically, this may be implementedusing known technology, such as simple moving averaging or weightedmoving averaging along the reference contour line, or curveapproximation. FIG. 28(b) illustrates an example of weighted movingaveraging using the Hann window as weight.

Thereafter in step S2704, the edge extraction parameter generation unit2613 determines a first edge extraction parameter P1 which is the edgeextraction parameter corresponding to the smoothed reference contourline (see FIG. 28(c)). The first edge extraction parameter P1 is aunique value for each reference edge. The process of step S2704 issimilar to the process of step S602 according to first embodiment, andinvolves determining an edge extraction parameter corresponding to thesmoothing reference edge position on the same brightness profile as thatduring reference edge extraction. In the present embodiment, on whichside of the image contour line the length measuring edge is extracted isdetermined by the dimension measuring recipe in advance. Thus, when theposition of the smoothing reference edge is not included in the intervalof 0% to 100% on the brightness profile, the edge extraction parameteris “0%” if displaced on the 0% side; if displaced on the 100% side, theedge extraction parameter is “100%”.

In step S2705, the edge extraction parameter generation unit 2613smoothes the first edge extraction parameter P1 to determine a secondedge extraction parameter P2 (see FIG. 28(d)). The second edgeextraction parameter P2 is a unique value for each reference edge.Specifically, the smoothing of the first edge extraction parameter P1may be implemented using known technology, such as simple movingaveraging or weighted moving averaging along the reference contour line,or curve approximation. FIG. 28(d) illustrates an example of simplemoving averaging.

In step S2706, the edge extraction parameter generation unit 2613determines the difference between the first edge extraction parameter P1and the second edge extraction parameter P2 (see FIG. 28(e)).Specifically, the absolute value of “P1−P2” is computed for eachreference edge.

In step S2707, the edge extraction parameter generation unit 2613determines, based on the difference, the ratio of contribution of eachof the predetermined edge extraction parameter and the first edgeextraction parameter. Specifically, by using the smaller of thedifference D and the predetermined threshold value TD, namely a valueDc, the ratio of contribution W0 of the predetermined edge extractionparameter is computed according to “(TD−Dc)/TD”, and the ratio ofcontribution W1 of the first edge extraction parameter is computedaccording to “Dc/TD”. Namely, when the difference between the first edgeextraction parameter and the second edge extraction parameter isrelatively small, the ratio of contribution of the predetermined edgeextraction parameter is relatively increased. When the differencebetween the first edge extraction parameter and the second edgeextraction parameter is relatively large, the ratio of contribution ofthe first edge extraction parameter is relatively increased. Ifinterpreted more intuitively, the predetermined edge extractionparameter is valued highly with respect to a portion where a change inthe edge extraction parameter is locally large. On the other hand, withrespect to a portion where the change in edge extraction parameter islocally large, because it can be considered that the influence of noiseand the like is large, the ratio of contribution of the first edgeextraction parameter is increased so as to obtain an edge extractionparameter such that a dimension measurement edge can be extracted nearthe smoothing reference edge.

During the computation of the ratio of contribution, the smaller of thedifference D and the predetermined threshold value TD, namely the valueDc (see FIG. 28(e)) is used for the following reason. Specifically,while the intension of determining the contribution ratios is todetermine an edge extraction parameter such that the edge for dimensionmeasurement can be extracted near the smoothing reference edge withrespect to a portion where the influence of noise and the like is large,it is considered appropriate, with respect to a portion having adifference of certain degree or more, to adopt the position of thesmoothing reference edge regardless of the magnitude of the difference.

In step S2708, the edge extraction parameter generation unit 2613, basedon the calculated ratios of contribution, determines the edge extractionparameter for dimension measurement (see FIG. 28(f)). Specifically, anedge extraction parameter Pmsr for dimension measurement is determinedas a weighted average of the predetermined edge extraction parameter P0and the first edge extraction parameter P1 according to“Pmsr=W0×P0+W1×P1”. The edge extraction parameter Pmsr for dimensionmeasurement is a unique value for each reference edge, and is determinedusing the corresponding first edge extraction parameter P1 for eachreference edge.

When a minimum value Pmin and a maximum value Pmax of the edgeextraction parameter is designated by the operator of the operationterminal 120 using an input interface and the like as will be describedlater (see FIG. 29) or designated by the dimension measuring recipe, thevalue of the edge extraction parameter Pmsr for dimension measurementthat has been determined by weighted averaging is corrected as needed.Specifically, if the value of the edge extraction parameter Pmsr fordimension measurement determined by weighted averaging is smaller thanPmin, the value of the edge extraction parameter Pmsr for dimensionmeasurement is corrected to be equal to Pmin. If the value of the edgeextraction parameter Pmsr for dimension measurement determined byweighted averaging is greater than Pmax, the value of the edgeextraction parameter Pmsr for dimension measurement is corrected to beequal to Pmax.

In step S2709, the dimension measuring contour line forming unit 2614,using the edge extraction parameter Pmsr for dimension measurement,determines a contour line for measuring dimension from the SEM image(see FIG. 28(g)). Specifically, on the brightness profile acquired foreach reference edge in step S2702, the length measuring edge fordimension measurement is determined using the edge extraction parameterPmsr for dimension measurement corresponding to the reference edge.

After the contour line for measuring dimension is determined using theedge extraction parameter Pmsr for dimension measurement, geometricsmoothing may be performed (see FIG. 28(h)). The smoothing is performedfor the purpose of mitigating the phenomenon in which the portion thathas originally been smooth is made continuously indifferentiable by thethreshold value processes of step S2707 and step S2708. Thus, a filterhaving a small radius may be used for implementation. FIG. 28(h)illustrates an example of using the Hann window of a diameter of 3.

For comparison, FIG. 28(i) illustrates a contour line determined usingan edge extraction parameter determined based not on the difference inedge extraction parameters but on the difference in distance in theprocess of step S2706 to step S2707. When the respective contour linesof FIG. 28(b), FIG. 28(h), and FIG. 28(i) that have been generated basedon FIG. 28(a) are compared, it can be seen that FIG. 28(b) and FIG.28(h) are superior from the viewpoint of decreasing the influence of anexceptional value or noise present in the interval 2801, while FIG.28(h) is superior from the viewpoint of high traceability to the contourshape in the interval 2802. This is an effect obtained by the fact thatthe smoothing is performed using not just simple geometric informationbut also reflecting brightness profile information.

In step S2710, the pattern dimension measurement unit 2615 measures thedimension of the pattern using the contour line for measuring dimension.The content of the process of step S2710 is similar to that according toconventional technology. For example, the distance between correspondinglength measuring edges in the range of the length measuring cursor ismeasured, and statistics of the distances, such as their average value,maximum value, minimum value, and the like, are determined as adimension measurement result. After the process of step S2710, theoperating/processing device 2610 ends the dimension measurement process.

FIG. 29 illustrates examples of the input interface for the processparameter set by the operator of the operation terminal 120 in thedimension measuring device according to the present embodiment. In FIG.29(a), in addition to the edge extraction parameter 2901 used in theprocess of step S2702 of FIG. 27, a variation range of the edgeextraction parameter used in the process of step S2708 of FIG. 27 isdesignated using an upper limit value 2902 and a lower limit value 2903.In FIG. 29(b), in addition to the edge extraction parameter 2901 used inthe process of step S2702 of FIG. 27, a variation range of the edgeextraction parameter used in the process of step S2708 of FIG. 27 isdesignated by a relative value 2904. Thus, by setting the range of thevariation range, the phenomenon in which the contour line for measuringdimension is excessively smoothed can be prevented. The edge extractionparameter 2901, the upper limit value 2902, the lower limit value 2903,and the relative value 2904 in FIG. 29 are examples of threshold valuesin the case of threshold value method (i.e., values in % where theminimum value is 0% and the maximum value is 100%). When dimensionmeasurement is implemented by a method other than the threshold valuemethod, the above values may be suitably modified to values suitable forthe particular technique. The input interface for the process parameteris also not limited to the above examples.

FIG. 30 illustrates a measurement result presenting method for thedimension measuring device according to the present embodiment,illustrating the content displayed on the display device of theoperation terminal 120. In the case of line width measurementillustrated in FIG. 30(a), the length measuring cursor 3001 is disposedand then measurement is implemented. As a result, an image illustratedFIG. 30(b) is presented to the operator of the operation terminal 120.As shown in FIG. 30(b), in the present embodiment, in addition to thedimension measurement result, such as an average dimension value, thathas conventionally been presented, values such as an average value, thestandard deviation a, the minimum value, and the maximum value of theedge extraction parameter for dimension measurement are also presented.Thus, the operator of the operation terminal 120 can grasp theappropriateness of the edge extraction parameter used for dimensionmeasurement. The operator of the operation terminal 120 can also utilizethe measurement result as information that is not directly reflected inthe dimension value measured using an extracted edge itself but that isindicative of a “region having a different state from other regions”,such as a change in the brightness profile shape due to a change in sidewall shape. The values presented with regard to the edge extractionparameter for dimension measurement are not limited to the aboveexamples and may include any value capable of providing any of the aboveeffects.

Thus, according to the present embodiment, an edge extraction parametersuitable for dimension measurement is determined for each referenceedge, and dimension measurement is performed using an edge extractedwith the use of the edge extraction parameter. In this configuration,the influence of noise or small roughness can be decreased, wherebymeasurement value reliability can be increased.

In the present embodiment, the edge extraction parameter value is notlower than 0% and not more than 100%. However, the embodiment of thepresent invention is not limited to the above, and may be defined in thesame way as the first embodiment. While the present embodiment has beendescribed with reference to the example of measurement of dimensionconcerning a line pattern, the pattern as the object of dimensionmeasurement is not limited to the above, and the embodiment may also beapplied when measuring a hole pattern diameter and the like, forexample.

Modification of the Second Embodiment

The dimension measuring device according to the second embodiment may beapplied to an exposure condition measuring device that determines anexposure condition on the basis of a model that is created in advancefrom image data obtained by imaging a measurement object pattern, usingan FEM wafer.

In the field of semiconductor manufacturing, as miniaturizationadvances, the demand for critical dimension uniformity (CDU) alsoincreases. In order to achieve high CDU, it is considered necessary notonly to find the optimum exposure conditions (the focal point positionand the amount of exposure) using an FEM wafer but also to executeexposure condition management for compensating for the influence ofprocess variations, i.e., “quantification” of errors in the focal pointposition and the amount of exposure. For the quantification, an exposurecondition measuring device has been proposed that determines theexposure conditions on the basis of a model that is created in advancefrom image data obtained by imaging a measurement object pattern, usingan FEM wafer. In the exposure condition measuring device, from the imagedata obtained by imaging a predetermined position on the FEM wafer, orimage data obtained by imaging the measurement object pattern, severaltypes of dimension feature quantities are determined that reflect apattern dimension change accompanying a change in the focal pointposition and the amount of exposure, or a change in the cross sectionshape of the photo resist. Then, a model is created using such dimensionfeature quantities, or the dimension feature quantities are applied tothe model, so as to measure the exposure conditions.

As described above, as the process rule evolves and the patterndimension becomes smaller, the influence of length measurement valuevariations on the pattern dimension due to edge roughness accompanyingside wall irregularities of the photo resist becomes relatively large,reducing model estimation accuracy. Thus, for example, when a dimensionfeature quantity is determined by conventional technology, the dimensionmeasuring device according to the second embodiment may be used tocreate a model using measurement values in which the influence of smalledge roughness is decreased. As a result, a model with higherreliability can be obtained, whereby the reliability of exposurecondition measurement values can be increased.

Further, in the present modification, an example of estimation ofexposure conditions on the basis of a feature quantity obtained bytwo-dimensional shape measurement will be described. It is known that asfocus changes, the shape of a pattern also changes. According to ananalysis by the inventor, the element of shape change can also be usedfor the estimation by adopting two-dimensional shape evaluation usingcontour shape, whereby an estimation result with higher reliability canbe obtained.

It is known that, as a general tendency concerning exposure conditionvariation, the cross-sectional shape of a side wall becomes downwardlyconvex in the case of an upper focal point (plus focus), while thecross-sectional shape of the side wall becomes upwardly convex in thecase of a lower focal point (minus focus). Accordingly, in the exposurecondition measuring device, it is effective, for increasing themeasurement accuracy, to use a feature quantity in which roundness of apattern upper part or tapering of a pattern lower part is reflected.

According to an analysis by the inventor, in order to reflect theirregularities in the cross-sectional shape of a side wall in thefeature quantity, at least three length-measuring contour lines arenecessary. Further, in order to reflect the roundness of a pattern upperpart or tapering of a pattern lower part, it is necessary to use threeor more length-measuring contour lines across the position of thehighest pixel value on the brightness profile; namely, a total of fiveto six length-measuring contour lines are necessary. The purpose of thelength-measuring contour lines is to have the side wall shape reflectedin the feature quantity. Thus, it is preferable to form thelength-measuring contour lines by determining a plurality of lengthmeasuring edges from the same brightness profile, rather thanindependently determining the length-measuring contour lines. Theposition and direction of brightness profile acquisition may bedetermined based on the design data or an image contour line. Theprocess of determining the length-measuring contour lines aftergeneration of the brightness profile is similar to the secondembodiment, and executed for each of a plurality of predetermined edgeextraction parameters.

After the length-measuring contour lines are determined, a dimensionfeature quantity is determined using the determined length-measuringcontour lines. As the dimension feature quantity, there may be used astatistic of EPE (such as an average value or standard deviation) basedon comparison of the length-measuring contour lines; a statistic (suchas an average value or standard deviation) of EPE based on comparison ofa reference contour line shape determined from the design data and eachof the length-measuring contour lines; the area of a region enclosed bythe length-measuring contour lines; or, in the case of a hole pattern, ahole diameter determined from the length-measuring contour lines.

Thus, according to the present modification, during exposure conditionmeasurement, an appropriate edge extraction parameter is used whendetermining the length-measuring contour lines, or a dimension featurequantity obtained by two-dimensional shape measurement using a plurality(three or more) of length-measuring contour lines is used, whereby anexposure condition estimation result with higher reliability can beobtained.

The method of estimating the exposure condition from a plurality ofdimension feature quantities is not limited to the illustrated examples.For example, multiple-regression analysis technique may be used.

Third Example Third Embodiment

In the following, a third embodiment will be described with reference toFIG. 31 to FIG. 34. The present embodiment represents an example of adimension measuring device which may be preferably used for the purposeof quantifying and evaluating the two-dimensional shape of a measurementobject pattern by shape comparison with a reference contour shape. Inthe case of quality management based on one-dimensional dimension,evaluation can be made by comparison with a reference dimension value.However, in the case of quality management based on two-dimensionalshape, it is necessary to evaluate by comparison with the shape of thereference contour line. Normally, evaluation is made by comparison ofthe shape of a given contour line as an evaluation reference with theshape of a contour line determined from an image obtained by imaging apattern as the object of evaluation. In this case, there is a problemsimilar to that of the second embodiment when the contour line isdetermined from the image. The shape of the evaluation reference contourline may be generated based on the design data, or the shape may begenerated using image data obtained by imaging one or more non-defectiveproducts, as will be described in the following examples.

As an example of the shape generated on the basis of the design data, acontour shape is determined by lithography simulation. The shape may bedetermined by geometrically deforming the design data in such a manneras to simulate the contour shape of a pattern expected to be formed onthe wafer, such as by rounding a corner portion of the design data(layout pattern).

An example of the shape generated using image data obtained by imagingone or more non-defective products is a contour shape extracted from oneimage obtained by imaging a non-defective product determined to be “themost desirable shape” by the operator of the operation terminal.Further, one contour shape suitable as an evaluation reference may bedetermined using a plurality of contour shapes extracted from aplurality of images obtained by imaging each of a plurality ofnon-defective products.

According to the present embodiment, in order to avoid confusionconcerning the use of terms, the shape of the reference contour linedescribed above will be uniformly referred to as “design pattern”regardless of whether the shape is one generated based on the designdata. This is due to the fact that, in the present embodiment, thepattern as a reference at the time of forming the length-measuringcontour line (i.e., the pattern representing the position of an ideallength-measuring contour line assumed to be preferable for dimensionmeasurement) differs from the pattern as a reference at the time ofshape evaluation using the length-measuring contour line. Thus, theterms “reference pattern”, “reference contour line”, and “referenceedge” will be used for the former, while “design pattern”, “designcontour line”, “design edge” will be used for the latter.

Compared with the first embodiment, the major differences are that thereis a relatively large discrepancy between the contour shape extractedfrom the design data and the contour shape extracted from the SEM imagebecause of the use of an SEM image obtained by imaging at a relativelyhigh magnification ratio, and that it is necessary to obtain aquantified evaluation value as a contour shape comparison result. Thedetails will be described in the following.

FIG. 31 illustrates a configuration of a dimension measuring deviceaccording to the present embodiment. In FIG. 31, portions similar tothose of FIG. 1 will be designated with similar signs to those of FIG. 1and their detailed description will be omitted. Also, portions similarto those of FIG. 26 will be designated with similar signs in FIG. 26 andtheir detailed description will be omitted.

An operating/processing device 3110 according to the present embodimentincludes the memory 111; an initial setting unit 3111 that executes theprocess of step S3201 and the like of FIG. 32; a reference contour lineforming unit 3112 that executes the process of step S3202 and the likeof FIG. 32; an edge extraction parameter generation unit 2613 thatexecutes the process of step S3203 and the like of FIG. 32 (namely, theprocess of step S2703 to S2708 of FIG. 27); a dimension measuringcontour line forming unit 3113 that executes the process of step S3204and the like of FIG. 32; and an inter-pattern dimension measurement unit3114 that executes the process of step S3205 and the like of FIG. 32.Based on the SEM image input from the imaging device 100 and the designdata concerning the pattern formed on the sample 101 g, a dimensionevaluation value for the pattern formed on the sample 101 g (such as anaverage value, a standard deviation, the maximum value and the like ofthe distance between each edge of a contour line determined from the SEMimage and a reference contour line) is determined to evaluate thequality of the pattern formed on the sample 101 g. Information necessaryfor the process executed in the operating/processing device 3110 arestored in the memory 111 in the operating/processing device 3110 as adimension measuring recipe. The recipe includes an operating program forcausing the dimension measuring device to be automatically operated. Therecipe is stored in the memory 111 or an external storage medium foreach type of sample as the object of measurement, and read as needed.

The operating/processing device 3110 is also connected to the operationterminal 120. The operating/processing device 3110 receives an inputfrom the operator of the operation terminal 120 via an input means ofthe operation terminal 120, and modifies the content of the measurementprocess as needed, or displays a measurement result and the like on adisplay device of the operation terminal 120. These functions areimplemented using a graphical interface called “GUI”, for example.

FIG. 32 is a flowchart of an operation of the dimension measuring deviceaccording to the present embodiment.

As the dimension measurement process is started, initially, in stepS3201, the initial setting unit 3111 performs initial setting of an SEMimage as the object of processing and design data as a reference forcomparison evaluation. Specifically, the initial setting unit 2611initially acquires an SEM image from the imaging device 100 andimplements preprocessing as needed. The preprocessing includes, forexample, a smoothing process for noise removal. The preprocessing may besuitably implemented using known technology. In the followingdescription of the present embodiment, the SEM image that has beensubjected to preprocessing as needed will be simply referred to as “SEMimage”. The initial setting unit 2611 then reads the design datacorresponding to a recipe-designated range from the from storage device130, and executes a design data deforming process as needed, such as apattern figure edge rounding process, generating a design pattern as acomparison evaluation reference. Then, the initial setting unit 2611performs positioning of the SEM image and the design pattern. Theprocess of positioning the SEM image and the design pattern may beimplemented using known technology. For example, a contour line isextracted from the SEM image and matched with the design pattern.

In step S3202, the reference contour line forming unit 3112 determines areference contour line using a predetermined edge extraction parameter.As the predetermined edge extraction parameter, there may be used avalue designated by a dimension measuring recipe stored in the memory111 and the like of the operating/processing device 3110, or a valueinput from the operator via the input means of the operation terminal120 may be used.

Because it is assumed that there is a large discrepancy between thecontour shape extracted from the design data and the contour shapeextracted from the SEM image, the reference contour line is determinedbased on an image contour line. Namely, after an image contour line isdetermined from the SEM image using known technology, edges are disposedat regular intervals along the image contour line. Then, at the positionof the edges, a brightness profile is acquired in a directionperpendicular to the direction of the tangent to the image contour lineto determine the reference contour line.

In step S3203, the edge extraction parameter generation unit 2613determines an edge extraction parameter Pmsr for dimension measurementon the basis of the reference contour line and the SEM image. Theprocess of step S3203 is similar to the process of step S2703 to S2708in the second embodiment.

In step S3204, the dimension measuring contour line forming unit 3113determines a length-measuring contour line for dimension measurementfrom the SEM image using the edge extraction parameter Pmsr fordimension measurement. Specifically, on the brightness profile acquiredin step S3202 for each reference edge, the length measuring edge fordimension measurement is determined using the edge extraction parameterPmsr for dimension measurement corresponding to the reference edge.

In step S3205, the inter-pattern dimension measurement unit 3114measures the dimension between the length-measuring contour line fordimension measurement and the design pattern to determine a dimensionevaluation value. The dimension measurement is implemented bydetermining the closest point on the design pattern with respect to eachlength measuring edge. At this time, the design pattern may be handledas a polygon as is, or as a set of design edges disposed at regularintervals, as in the first embodiment. When the design pattern ishandled as a set of design edges, development of erroneous associationmay be prevented by the following method. Namely, when a point on firstcontour data and a point on second contour data are associated with eachother, first association information of the point on the first contourdata and the point on the second contour data is generated. Then,consistency of an association relationship included in the firstassociation information is determined, and the association relationshipthat does not have consistency is corrected to generate secondassociation information. The dimension measurement may be implemented bya method disclosed in Patent Literature 1, for example, using the designpattern as a reference.

After completion of the association between the length measuring edgefor dimension measurement and the edge on the design pattern, theinter-pattern dimension measurement unit 3114 determines statisticsdepending on the purpose of evaluation, such as an average value, astandard deviation, and the maximum value of EPE corresponding to eachof the length measuring edges for dimension measurement, obtainingdimension evaluation values. As needed, a region as the object ofevaluation, i.e., a region with high risk of defect development may beset as a region of interest (ROI), and the process may be implementedonly for the length measuring edges for dimension measurement that arepresent in the ROI. The setting of the ROI may be made using a regiondesignated by the dimension measuring recipe stored in the memory 111 ofthe operating/processing device 3110 and the like. Alternatively, aregion designated by the operator via the input means of the operationterminal 120 may be used.

When the average value of EPE is adopted as the dimension evaluationvalue, “the average degree of divergence of the length-measuring contourline for dimension measurement from the design pattern” is expressed asa numerical value. Thus, this is preferable for the purpose ofevaluating the degree of expansion or contraction of a pattern figuredue to exposure condition variations. When the standard deviation of EPEis adopted as the dimension evaluation value, for example, “the degreeof distortion of the shape of the length-measuring contour line fordimension measurement with respect to the shape of the design pattern”is expressed as a numerical value. Thus, this is preferable for thepurpose of evaluating the extent of crumbling of a pattern figure due toexposure condition variation. Accordingly, these dimension evaluationvalues are preferable for the purpose of process window analysis. Whenthe maximum value of EPE is adopted as the dimension evaluation value,for example, “whether the shape of the length-measuring contour line fordimension measurement as a whole is within a tolerance with respect tothe shape of the design pattern” can be determined. Thus, this ispreferable for the purpose of non-defective product inspection.

The dimension evaluation value is not limited to any one of thestatistics that have been described by way of example concerning theEPE. The dimension evaluation value may be another index based on ameasured dimension, or a plurality of values may be retained as vectorvalues. After the process of step S3205, the operating/processing device3110 ends the dimension measurement process.

FIG. 33 illustrates an operation of the dimension measuring deviceaccording to the present embodiment.

FIG. 33(a) illustrates a design pattern. FIG. 33(b) illustrates aninspection image obtained by imaging a resist after development. Due tothe presence of resist residue around a recess portion 3300, a lightwhite band is observed around the boundary region 3301. In such a state,a phenomenon develops in which a portion that does not appear to be adefect at the stage of inspection of the developed wafer by imagingpresents itself as a defect upon inspection by imaging the wafer afteretching. According to an analysis by the inventor, the phenomenon is dueto the fact that the resist residue around the recess portion 3300 hassuch a small thickness and not even stepped that the white band does notappear clearly.

FIG. 33(c) shows a contour line for measuring dimension formed from theinspection image of FIG. 33(b). FIG. 33(d) shows an image obtained byimaging the same region as that of FIG. 33(b) that has been etched. Theimage shows the development of a defect that is difficult to expect bysimply observing the shape of the contour line of FIG. 33(c). FIG. 33(e)shows the design pattern and the contour line for measuring dimensionthat have been drawn superposed upon each other. By measuring thedimension between the “two contour lines that have been positioned”, adimension evaluation value that contributes to the evaluation of thetwo-dimensional shape of the measurement object pattern, such as anaverage value of EPE or a standard deviation, is calculated. FIG. 33(f)shows a part of FIG. 33(e) as enlarged, in which the distance of a linesegment 3310 is an example of EPE.

FIG. 33(g) shows an image in which a marker 3320 is superposed at aportion determined to have an abnormal edge extraction parameter.Specifically, for example, an average value and a standard deviation ofedge extraction parameters corresponding to a reference edge in thevicinity of a reference edge of interest are determined, and an edgeextraction parameter normal range is determined using the values. If theedge extraction parameter of the reference edge of interest is notincluded in the calculated normal range, abnormality is determined. Themethod of determining whether the edge extraction parameter is abnormalis not limited to the above.

The contour line for measuring dimension is determined based on theshape of the design pattern. Thus, no contour line for measuringdimension is formed in a portion with a phase structure different fromthe shape of the design pattern, such as the white band in the boundaryregion 3301. Thus, the abnormality would not be determined as a defectsolely from the viewpoint of EPE. Further, a portion such as the whiteband in the boundary region 3301 is often not clearly present on theimage. Thus, a contour line extraction approach involving, for example,extraction of a portion that appears relatively bright in apredetermined region on the image is often not capable of stable contourline detection due to a difficulty in setting parameters, such as athreshold value.

According to the present embodiment, the edge extraction parameter perse is used as an evaluation index for determining “whether the state isdifferent from other regions”. In this way, even in the above-describedcases, the portion that could possibly be a defect can be detected aslong as the portion is present in the vicinity of the design pattern.

FIG. 34 illustrates a measurement result presenting method for thedimension measuring device according to the present embodiment,illustrating a case in which the dimension measuring device according tothe present embodiment is applied for the evaluation of an FEM wafer foranalyzing a process window.

In FIG. 34, the rectangular regions that are painted over, such as ashot region 3401, indicate the presence of a location determined to be a“defect” by a dimension evaluation value-based evaluation in anevaluation using an SEM image corresponding to the exposure conditionscorresponding to the relevant region. The rectangular regions drawn withbold frames, such as a shot region 3402, indicate the absence of alocation determined to be a “defect” by the dimension evaluationvalue-based evaluation while indicating the presence of a locationdetermined to have an edge extraction parameter abnormality in theevaluation using the SEM image corresponding to the exposure conditionscorresponding to the relevant region. The other rectangular regions,such as a shot region 3403, indicate the presence of neither a locationdetermined to be a “defect” by the dimension evaluation value-basedevaluation nor a location determined to have an edge extractionparameter abnormality in the evaluation using the SEM imagecorresponding to the exposure conditions corresponding to the relevantregion. When the optimum exposure conditions are estimated in view ofsuch measurement results, the process window is defined assuming that,in addition to the portions similar to the shot region 3401, theportions similar to the shot region 3402 are “inappropriate”, wherebythe reliability of the optimum exposure condition estimation result canbe increased.

Thus, in addition to the evaluation based on the dimension evaluationvalue, the edge extraction parameter per se is added to the evaluationindex. In this way, in addition to the presence or absence of a cleardefect that can be determined by contour line shape comparison,locations with relatively high risk of defect development, such as alocation where the side wall shape is different from other regions or alocation where the state of resist residue at a bottom portion isdifferent from other regions, can be detected.

FIG. 34 illustrates an example of the measurement result presentingmethod, and the measurement result presenting method is not limited tothe above even when limited to the purpose of FEM wafer evaluation. Forexample, as long as the risk level can be grasped for each exposurecondition, the shot region 3401 may be drawn with a red frame, the shotregion 3402 may be drawn with a yellow frame, and the shot region 3403may be drawn with a green frame for presentation.

Thus, according to the present embodiment, the edge extraction parametersuitable for dimension measurement is determined for each referenceedge, and the dimension between patterns is measured using an edgeextracted with the use of the edge extraction parameter. In thisconfiguration, even for the purpose of measuring the dimension betweenpatterns, the influence of noise or small roughness can be decreased,whereby the measurement value reliability can be increased.

Further, in addition to the evaluation based on the dimension evaluationvalue, the edge extraction parameter per se is used as an evaluationindex. In this way, in addition to the presence or absence of a defectthat can be determined by contour line shape comparison, the “locationswith relatively high risk of defect development that cannot be detectedsolely based on a dimension evaluation value”, such as a location wherethe side wall shape is different from other regions or a location wherethe state of resist residue at a bottom portion is different from otherregions, can be detected.

In the present embodiment, in the process of step S3205, theinter-pattern dimension measurement unit 3114 determines the dimensionevaluation value between the length-measuring contour line for dimensionmeasurement and the design pattern after the length measuring edge fordimension measurement and an edge on the design pattern are associatedwith each other. However, the embodiment of the present invention is notlimited to the above. For example, the dimension evaluation value may bedetermined without associating the length measuring edge for dimensionmeasurement with the edge on the design pattern. Specifically,initially, a distance conversion image is generated based on theinformation about the position of the edge on the design pattern. Thegeneration of the distance conversion image may be implemented by knownmethod. Then, with reference to the pixel value of the distanceconversion image corresponding to the position of the length measuringedge for dimension measurement, the distance to the edge on the designpattern closest to the length measuring edge is determined as an EPEvalue corresponding to the length measuring edge. Thereafter, statisticssuch as an average value, a standard deviation, and the maximum value ofEPE corresponding to each of the length measuring edges for dimensionmeasurement may be determined as dimension evaluation values dependingon the purpose of evaluation, and a ROI may be set as needed when thedimension evaluation value is determined and only the length measuringedges for dimension measurement that are present in the ROI may beprocessed, as in the above-described process of step S3205. Thus, thedimension evaluation value is determined without associating the lengthmeasuring edge for dimension measurement and the edge on the designpattern with each other. By adopting such configuration, a dimensionevaluation value can be determined in a shorter processing time thanwhen the dimension evaluation value is determined after the both areassociated with each other. When the dimension evaluation value isdetermined without associating the length measuring edge for dimensionmeasurement and the edge on the design pattern with each other, thepossibility of erroneous association increases in the region in whichthe design pattern is densely present, whereby the reliability of thedimension evaluation value decreases. Accordingly, the presentmodification may be preferably applied for dimension measurement under acondition such that the design pattern is not densely present, such aswhen the SEM image is acquired by imaging at a higher magnificationratio.

The method of generating the length-measuring contour line in step S3202is not limited to the illustrated example. For example, as according tothe technology disclosed in the international publicationWO2011/152106A1, the position or direction for brightness profileacquisition may be determined on the basis of the image contour line andthe design pattern. Also, the method of determining the image contourline is not limited to the illustrated example. For example, a regiondividing approach may be used for the determination.

Fourth Example Fourth Embodiment

In the following, a fourth embodiment will be described with referenceto FIG. 34 to FIG. 38. The present embodiment represents an example of adimension measuring device that is simply calibrated so as to decreasethe influence of machine difference between different dimensionmeasuring devices or of temporal variation due to the state of thedimension measuring device on the measurement value, and to obtain adimension close to the reference dimension.

The shape of the brightness profile may be varied by a machinedifference between devices or by temporal variation in the state of thedevice. For example, the manner of expansion of the shape of the profilemay differ from one device to another due to difference in resolution.Thus, when a common edge extraction parameter is used, the measurementvalue obtained using an edge extracted with the edge extractionparameter may have mutually different values.

The inventor, based on the assumption that the cause of the problem liesin the use of the same edge extraction parameter for determining theedge position in all devices or all device states, proposes the presentembodiment as an example by which the problem can be solved. In thepresent embodiment, the problem is solved by the followingconfiguration. A common reference wafer having a standard pattern isused to determine an edge extraction parameter conversion function inadvance by a prior calibration process. At the time of measurement, apredetermined edge extraction parameter designated by the dimensionmeasuring recipe or the operator of the operation terminal is changed bythe previously obtained edge extraction parameter conversion function,and then an edge is extracted.

The details will be described in the following.

[Configuration of Dimension Measuring Device According to FourthEmbodiment]

FIG. 35 illustrates a configuration of a dimension measuring deviceaccording to the present embodiment. In FIG. 35, portions similar tothose of FIG. 1 are designated with similar signs in FIG. 1, and theirdetailed description will be omitted.

A operating/processing device 3510 according to the present embodimentincludes the memory 111; an edge extraction parameter generation unit3511 that executes the parameter calibration process and the like ofFIG. 36; an initial setting unit 3512 that executes the process of stepS3801 and the like of FIG. 38; a dimension measuring contour lineforming unit 3513 that executes the process of step S3802 to S3803 andthe like of FIG. 38; and a pattern dimension measurement unit 3514 thatexecutes the process of step S3804 and the like of FIG. 38. Based on theSEM image input from the imaging device 100, the operating/processingdevice 3510 measures the dimension of the pattern formed on the sample101 g. Information necessary for the process executed in theoperating/processing device 3510, such as “how the dimension of whichportion of the pattern present at which position on the sample is to bemeasured”, is stored in the memory 111 in the operating/processingdevice 3510 as a dimension measuring recipe. The recipe includes anoperating program for causing the dimension measuring device to beautomatically operated. The recipe may be stored in the memory 111 or anexternal storage medium for each type of sample as the object ofmeasurement, and is read as needed.

The operating/processing device 3510 is also connected to the operationterminal 120. In response to an input from the operator via the inputmeans of the operation terminal 120, the operating/processing device3510 modifies the content of the measurement process as needed, ordisplays a measurement result and the like on the display device of theoperation terminal 120. These functions are implemented by a graphicalinterface called “GUI”, for example.

In the storage device 3530, there are stored a reference devicecharacteristics curve (a curve expressing the relationship between theedge extraction parameter and the dimension measurement value when thestandard pattern on the reference wafer is measured) that is created inadvance, and an edge extraction parameter conversion curve that iscreated in the parameter calibration process of FIG. 36 and that isreferenced in the dimension measurement process of FIG. 38.

[Operation of Edge Extraction Parameter Generation Unit 3511 of theFourth Embodiment]

FIG. 36 is a flowchart of an operation of the edge extraction parametergeneration unit 3511 included in the operating device of the dimensionmeasuring device according to the present embodiment.

As the parameter calibration process is started, the edge extractionparameter generation unit 3511, initially in step S3601, images thestandard pattern on the reference wafer using the imaging device 100 asthe object of calibration. From the obtained image, the edge extractionparameter generation unit 3511 determines a measurement value usingknown technique (such as a threshold value method) with respect to eachof a plurality of edge extraction parameters. The measurement value maybe determined for all values that the edge extraction parameters maytake, or the measurement value may be determined by selecting some ofthe edge extraction parameters.

As the standard pattern used for calibration, a longitudinal (directionperpendicular to the electron beam scan direction) line pattern may beused, or a hole pattern may be used. When the longitudinal line patternis used, calibration is performed preferentially with respect to thelateral direction dimension for which dimension accuracy can be easilyensured in SEM, and such that a dimension close to the referencedimension can be obtained. When the hole pattern is used, calibration isperformed both longitudinally and laterally in an averaged manner andsuch that a dimension close to the reference dimension can be obtained.In order to decrease the influence of noise, roughness and the like, aplurality of identical-shape patterns may be disposed and an averagevalue of their measurement values may be used for calibration.

Then, in step S3602, the edge extraction parameter generation unit 3511,using the measurement value determined in step S3601, determines acharacteristics curve of the imaging device 100 as the object ofcalibration using known technology. For example, the characteristicscurve is determined by broken line approximation from a set of pairs ofthe edge extraction parameters and the measurement values obtained instep S3601.

The edge extraction parameter generation unit 3511 then determines instep S3603 correspondence between the characteristics curve of thereference device and the characteristics curve of the device as theobject of calibration. For example, a dimension value of a standardpattern is determined from the edge extraction parameter value of thereference device using the characteristics curve of the referencedevice, and an edge extraction parameter of the device as the object ofcalibration that achieves the dimension value is determined using thecharacteristics curve of the calibration object device. The associationmay be determined for all values that the edge extraction parameters maytake, or for several selected edge extraction parameters.

Thereafter, the edge extraction parameter generation unit 3511 in stepS3604 determines the edge extraction parameter conversion curve usingknown technology. For example, the edge extraction parameter conversioncurve may be determined by broken line approximation from a set of pairsof the edge extraction parameters of the reference device obtained instep S3603 and their corresponding edge extraction parameters of thecalibration object device. After the process of step S3604, the edgeextraction parameter generation unit 3511 ends the parameter calibrationprocess.

FIG. 37 illustrates an operation of the edge extraction parametergeneration unit included in the operating device of the dimensionmeasuring device according to the present embodiment, particularly theprocess of step S3603 to step S3604. The parameter calibration processis a process for the purpose of determining an edge extraction parameterconversion curve for converting the edge extraction parameter of thereference device into the edge extraction parameter of the calibrationobject device.

Initially, with respect to the edge extraction parameter 3701 of thereference device, the characteristics curve of the reference device 3702that has been created and stored in the storage device 3530 in advanceis referenced, and a measurement value 3703 in an image obtained by thereference device that corresponds to the edge extraction parameter 3701of the reference device is determined (see FIG. 37(a)).

Then, from the measurement value 3703 in the image captured by thereference device, the characteristics curve of the calibration objectdevice 3704 determined in step S3601 to step S3602 is referenced, and anedge extraction parameter of the calibration object device 3705 thatcorresponds to the measurement value 3703 in the image captured by thereference device is determined (see FIG. 37(b)). With respect to theedge extraction parameter 3701 of the reference device, the edgeextraction parameter of the calibration object device 3705 isassociated, whereby a point 3706 of the reference device edge extractionparameter conversion curve 3707 that corresponds to the edge extractionparameter 3701 is determined (see FIG. 37(c)).

The above process is performed for all of the edge extraction parametersof the reference device, whereby the entirety of the edge extractionparameter conversion curve 3707 can be obtained.

[Process Flow of Dimension Measurement Process of the Fourth Embodiment]

FIG. 38 is a flowchart of an operation of the dimension measuring deviceaccording to the present embodiment.

As the dimension measurement process is started, initially, in stepS3801, the initial setting unit 3512 performs initial setting of the SEMimage as the object of measurement. The process executed by the initialsetting unit 3512 in step S3801 is similar to the process of step S2701executed by the initial setting unit 2611 in the second embodiment. Inthe following description of the present embodiment, the SEM image thathas been subjected to preprocessing as needed will be simply referred toas “SEM image”.

Then, the dimension measuring contour line forming unit 3513 in stepS3802 references the edge extraction parameter conversion curve storedin the storage device 3530 (i.e., “calibration data”), and determinesthe edge extraction parameter for dimension measurement using apredetermined edge extraction parameter that is either designated by thedimension measuring recipe stored in the memory 111 and the like of theoperating/processing device 3510, or input from the operator via theinput means of the operation terminal 120.

In step S3803, the dimension measuring contour line forming unit 3513,using the edge extraction parameter for dimension measurement determinedin step S3801, determines the length-measuring contour line fordimension measurement by the known technique used at the time ofcalibration.

In step S3804, the pattern dimension measurement unit 3514, using thecontour line for measuring dimension determined in step S3803, measuresthe dimension of a pattern. After the process of step S3804, theoperating/processing device 3510 ends the dimension measurement process.

Thus, according to the present embodiment, the influence on themeasurement value due to machine difference between dimension measuringdevices or temporal variation in the state of the dimension measuringdevice can be decreased, and the dimension measuring device can besimply calibrated so that a dimension close to a reference dimension canbe obtained.

The data structure of the edge extraction parameter conversion curve isnot limited to the illustrated examples. The data structure of the edgeextraction parameter conversion curve may be retained as informationsuch that an edge extraction parameter of the calibration object devicethat corresponds to the edge extraction parameter of the referencedevice can be determined. For example, the data structure may beretained as a look-up table. Alternatively, a broken line orapproximation curve parameter may be retained.

The edge extraction parameter conversion curve may be determined foreach of the imaging parameter of the reference device and thecalibration object device. The edge extraction parameter conversioncurve may be retained in the form of a table having the imagingparameter of the reference device and the imaging parameter of thecalibration object device as search keys. Then, a required edgeextraction parameter conversion curve may be suitably selected and used.In this configuration, a dimension close to a reference dimension can beobtained even when different imaging parameters are used.

If the influence of spherical aberration of an electronic optical systemcannot be disregarded, the edge extraction parameter conversion curvemay be determined as a function of the position of passage through anobjective lens. Specifically, after edge extraction parameter conversioncurves are determined at several positions similarly to the presentembodiment, and then interpolation may be performed using knowntechnology so as to determine an edge extraction parameter conversioncurve as a continuous function with respect to the position. By adoptingsuch configuration, even when the influence of spherical aberration ofthe electronic optical system cannot be disregarded, a dimension closeto a reference dimension can be obtained.

The method of determining the edge extraction parameter conversion curveis not limited to the illustrated examples. For example, instead ofdetermining via a measurement value, contour line shapes may becompared. Specifically, the edge extraction parameter conversion curvemay be determined by associating, with respect to a contour line thathas been determined from an image captured by the reference device usinga predetermined edge extraction parameter, an edge extraction parametersuch that a contour line that achieves a minimum EPE value can beextracted from an image captured by the calibration object device. Byadopting such configuration, an edge extraction parameter conversioncurve that may be preferably used when measuring a two-dimensional shapecan be determined. In this case, a reference contour line (the result ofextraction of a length-measuring contour line from an image of thestandard sample captured by the reference device) is stored in thestorage device 3530 as reference data.

Fifth Example Fifth Embodiment

In the following, a fifth embodiment will be described with reference toFIG. 39 to FIG. 42. The present embodiment represents an example of apattern inspecting device that may be preferably used in identifyingpattern location candidates that tend to be defective, using a pluralityof image data obtained by imaging inspection object patterns underdifferent exposure conditions or in different steps.

In the field of semiconductor manufacturing, in order to determine apermissible range of variation in focal distance and the amount ofexposure during pattern transfer, and determine a process window, anoptimum focal distance, and the amount of exposure and the like, a focusexposure matrix (FEM) wafer is used. The FEM wafer is a wafer on whichthe same pattern is printed while varying the focal point position andthe amount of exposure in a matrix from one shot (one unit of exposure)to another. During evaluation for determining the process window, forexample, with respect to each image obtained by imaging an evaluationobject pattern corresponding to each shot, a contour shape determinedfrom an edge extracted using a predetermined edge extraction parameterand a contour shape determined from design data are compared todetermine EPE. Then, the quality of the shot is determined based on anevaluation using values of the EPE, such as an average value, standarddeviation, and the maximum value.

The present embodiment proposes a pattern inspecting device fordetecting a location of a pattern with a shape that tends to be easilycrumbled by a change in exposure condition. In the pattern inspectingdevice, by using a plurality of images obtained by imaging an evaluationobject pattern present at corresponding positions on the FEM wafers areused, the behavior of a pattern when only the amount of exposure isvaried with a constant focal distance, or the behavior of a pattern whenonly the focal distance is varied with a constant amount of exposure iscompared. By detecting the pattern location with the shape that tends tobe easily crumbled by a change in exposure condition, namely, thelocation with small process margin, mask pattern improvements can bemade by feeding back the information.

In order to detect the location with the pattern that is readilycrumbled by a change in exposure condition, it is necessary to observe achange in pattern shape by two-dimensional shape comparison. However,when the exposure conditions are different, a pattern deformation on thewafer appears not only as a change in local shape but also as adimension change. Thus, in a method that has conventionally been usedfor evaluation for determining the process window, even when theconfiguration is such that a distribution of EPE is observed on ascreen, local amounts of deformation may become lost in global amountsof deformation, resulting in the problem of difficulty in capturing achange in shape.

The inventor, considering that the cause of the problem is that themethod of “evaluation based on comparison of the contour shapedetermined from an edge extracted using a predetermined edge extractionparameter and the contour shape determined from design data, withrespect to all of images obtained by imaging an evaluation objectpattern corresponding to each shot” is not suitable for the purpose ofdetecting a subtle difference in pattern shape, proposes the presentembodiment as a solution example. The details will be described in thefollowing.

FIG. 39 illustrates a configuration of a pattern inspecting deviceaccording to the present embodiment. In FIG. 39, portions similar tothose of FIG. 1 are designated with similar signs in FIG. 1, and theirdetailed description will be omitted.

An operating/processing device 3910 according to the present embodimentincludes the memory 111; an initial setting unit 3911 that executes theprocess of step S4001 and the like of FIG. 40; a reference patternforming unit 3912 that executes the process of step S4004 and the likeof FIG. 40; a simplex inspection unit 3913 that executes the process ofstep S4005 and the like of FIG. 40; a state update unit 3914 thatexecutes the process of step S4002 to S4003 and step S4006 to S4008 andthe like of FIG. 40; and an inspection result output unit 3915 thatexecutes the process of step S4009 and the like of FIG. 40. Based on aplurality of SEM images input from the imaging device 100, the patternformed on the sample 101 g is inspected. Information necessary for theprocesses executed in the operating/processing device 3910 are stored inthe memory 111 in the operating/processing device 3910 as an inspectionrecipe. The recipe includes an operating program for causing the patterninspecting device to be automatically operated. The recipe may be storedin the memory 111 or an external storage medium for each type of sampleas the object of inspection, and read as needed.

The operating/processing device 3910 is also connected to the operationterminal 120. As needed, in response to an input from the operator viathe input means of the operation terminal 120, the operating/processingdevice 3910 modifies the inspection process content or displays aninspection result and the like on the display device of the operationterminal 120. These functions are implemented by a graphical interfacecalled “GUI”, for example.

FIG. 40 is a flowchart of an operation of the pattern inspecting deviceaccording to the present embodiment.

As the pattern inspection process is started, in step S4001, the initialsetting unit 3911 implements initial setting for pattern inspection.Specifically, all of SEM images obtained by imaging an evaluation objectpattern on the FEM wafer corresponding to each shot are read, andpreprocessing is implemented as needed with respect to the SEM images.The preprocessing includes, for example, a smoothing process for noiseremoval. The preprocessing may be suitably implemented using knowntechnology.

Then, in step S4002, the state update unit 3914 initializes a defectregion list as an empty list, and further initializes a dead region asan empty set.

The defect region list includes information about regions that arefinally output as defect regions. For example, in the list, for eachregion determined to be a defect, the coordinates of the upper-leftcorner of a circumscribed rectangle of the region determined to be adefect, the width and height of the circumscribed rectangle, and imageinformation and the like in the circumscribed rectangle are registeredin association with information indicating “with respect to which SEMimage the determination of a defect has been made in the inspection”.

The dead region is a region outside the object of inspection in theinspection in step S4005. The region that has once been determined to bea defect due to the influence of exposure condition variation from theoptimum exposure condition is subject to a rapid degradation in patternshape as the exposure condition is further varied. The dead regionaccording to the present embodiment is provided to prevent theinspection process as a whole from being made unstable by including suchregion as the object of inspection.

Thereafter, in step S4003, the state update unit 3914 sets the value ofthe counter S, which is a counter for identifying a reference shot, to“0”.

In step S4004, using a predetermined edge extraction parameter, thereference contour line forming unit 3912 forms a reference contour linefrom the SEM image corresponding to the S-th shot. As in the secondembodiment, for the purpose of smoothing the generated contour line, thecontour line may be formed using a different edge extraction parameterfor each edge. As the predetermined edge extraction parameter, a valuedescribed in the inspection recipe stored in the memory 111 of theoperating/processing device 3910, or a value input from the operator viathe input means of the operation terminal 120 may be used.

In step S4005, the simplex inspection unit 3913, based on the referencecontour line formed in step S4004, inspects the SEM image correspondingto the (S+1)th shot. The process of step S4005 may be implementedsimilarly to the pattern inspection process in the pattern inspectingdevice according to the first embodiment. Because the S-th shot and the(S+1)th shot have close exposure conditions, the pattern shapes aresimilar at normal portions. Thus, by forming a contour line(length-measuring contour line) using an appropriate edge extractionparameter for each reference edge, only a portion with a different shapecan be detected as a defect during the inspection.

In step S4006, the state update unit 3914 registers informationconcerning all newly detected defect regions in the defect region list,and further adds the all newly detected defect regions to the deadregions.

In step S4007, the state update unit 3914 determines whether thecomparison has been completed for all of the pairs requiring comparison,by comparing the value of the counter S with the number of the SEMimages (which will be described later) as the object of inspection. Ifthe comparison has been completed for all of the pairs requiringcomparison (step S4007: YES), the operating/processing device 3910proceeds to the process of step S4009. If there is a pair for which thecomparison has not been completed (step S4007: NO), the state updateunit 3914 proceeds to step S4008 and increases the value of the counterS by “1”. Thereafter, the operating/processing device 3910 returns tostep S4004 and continues the processing.

In step S4009, the inspection result output unit 3915, with reference tothe defect region list, outputs the information about all of the defectregions that have been detected so far. After the process of step S4009,the operating/processing device 3910 ends the pattern inspectionprocess. As the defect region information, in addition to the positionand dimension, image information in the region and the like, informationabout “in the inspection of the SEM image corresponding to what numbershot the defect region has been determined” (namely, the value of “S+1”in the flowchart of FIG. 40) is also output. By providing suchinformation, the margin with respect to a change in the exposurecondition can be observed for each defect region.

FIG. 41 illustrates an inspection object designating method in thepattern inspecting device according to the present embodiment. In thepresent embodiment, the operator of the operation terminal 120 inputs,on a wafer map for an FEM wafer, for example, information foridentifying an SEM image 4100 corresponding to a shot with an optimumfocal point position and an optimum amount of exposure, and, of the SEMimages to be evaluated, information for identifying an SEM image 4103 ata position spaced apart the most from the SEM image 4100, using anappropriate graphical user interface (GUI) implemented on the operationterminal 120. The operating/processing device 3910, based on the inputinformation and using the initial setting unit 3911, searches for theshortest path connecting the SEM image 4100 and the SEM image 4103. Theoperating/processing device 3910 then sets the SEM image 4100, an SEMimage 4101, an SEM image 4102, and the SEM image 4103 including SEMimages on the shortest path as the object of inspection in the patterninspection process. The shortest path search may be performed bycreating a graph connecting, via sides, vertexes corresponding to theSEM images at four vicinity positions, using the SEM images on the FEMwafer corresponding to each shot as the vertexes, using knowntechnology. In the pattern inspection process according to the presentembodiment, as will be described later (see FIG. 42), inspection isimplemented, in the order along the shortest path and using adjacent SEMimages as a pair, with reference to an SEM image closer to the SEM imagecorresponding to the shot with the optimum focal point position and theoptimum amount of exposure.

The information input from the operation terminal 120 may be limited toinformation for identifying the SEM image 4100 corresponding to the shotwith the optimum focal point position and the optimum amount ofexposure. With respect to all SEM images on the wafer map of the FEMwafer, the shortest path from the SEM image 4100 may be searched for,and then the pattern inspection process may be implemented along theshortest path.

FIG. 42 illustrates an inspection method in the pattern inspectingdevice according to the present embodiment.

FIG. 42(a) illustrates an example of the process flow of FIG. 40 wherethe value of S is “0”; namely, the case where the SEM image 4100 and theSEM image 4101 are compared. This is an example where, when apredetermined edge extraction parameter is used, a contour lineillustrated by an image 4200 is extracted from the SEM image 4100, whilea contour line illustrated by an image 4201 is extracted from the SEMimage 4101. In this case, when the contour line extracted from the SEMimage 4101 using the contour line extracted from the SEM image 4100 as areference contour line is drawn superposed on the reference contourline, the state of an image 4210 is obtained, indicating that no defecthas been detected.

FIG. 42(b) illustrates an example of the process flow of FIG. 40 wherethe value of S is “1”; namely, where the SEM image 4101 and the SEMimage 4102 are compared. This is an example where, when a predeterminededge extraction parameter is used, a contour line illustrated by animage 4201 is extracted from the SEM image 4101, while a contour lineillustrated by an image 4202 is extracted from the SEM image 4102. Inthis case, when the contour line extracted from the SEM image 4102 usingthe contour line extracted from the SEM image 4101 as a referencecontour line is drawn superposed on the reference contour line, thestate of an image 4220 is obtained, where a region 4221 is extracted asa defect. Thus, information concerning the region 4221 is registered inthe defect region list, and the region 4221 is further added to the deadregions.

FIG. 42(c) illustrates an example of the process flow of FIG. 40 wherethe value of S is “2”; namely, where the SEM image 4102 and the SEMimage 4103 are compared. This is an example where, when a predeterminededge extraction parameter is used, a contour line illustrated by animage 4202 is extracted from the SEM image 4102, while a contour lineillustrated by an image 4203 is extracted from the SEM image 4103. Inthis case, when the contour line extracted from the SEM image 4103 usingthe contour line extracted from the SEM image 4102 as a referencecontour line is drawn superposed on the reference contour line, thestate of an image 4230 is obtained, where a region 4231 and a region4232 are extracted as defects. However, with regard to a region 4221,because it is a dead region, no defect determination is made.Accordingly, information concerning the region 4231 and the region 4232is registered in the defect region list, and further the region 4231 andthe region 4232 are added to the dead regions.

Thus, according to the present embodiment, inspection is performed bycomparing the contour line shapes of the dies of adjacent shots, wherecontour lines formed using an edge extraction parameter suitable forcomparison are used. In this way, local deformation can be detectedwithout being lost in global pattern thickening or thinning.

Further, the region determined to be a defect is set as a dead regionfor the next inspection, and the SEM image corresponding to each shot issuccessively evaluated in a direction such that the difference from theoptimum condition is increased while the dead region is successivelyupdated. In this configuration, not only the pattern location with thehighest risk of defect development, but also a pattern location having arelatively low but a certain degree of the risk of defect developmentcan be automatically analyzed. Thus, mask pattern improvements can bemade more efficiently.

When the exposure condition variation range is small and there is only aslight global pattern thickening or thinning, the SEM imagescorresponding to all shots may be inspected using a reference contourline determined from the SEM image having the optimum exposure conditionor a reference contour line determined from the design data.

As in the modification of the second embodiment, a plurality (three ormore) of length measuring edges may be determined from the samebrightness profile in units of the reference edge, and a plurality of(namely, three or more) length-measuring contour lines may be formed bylinking corresponding length measuring edges for evaluation. In thisconfiguration, while the evaluation concerning the respective contourlines is performed each independently, the determination of a defectregion is made upon determining a defect region in any one of thelength-measuring contour lines, and information about which contour linewas used in the inspection in which the defect region was determined isalso output.

Modification

While the embodiments of the present invention have been describedabove, the present invention is not limited to the embodiments. Thevarious configurations of the foregoing embodiments and modificationsmay be suitably combined and used as needed. In addition, theembodiments may be modified as follows, for example, without departingfrom the gist of the present invention.

For example, while in the embodiment the SEM image as the object ofinspection or measurement is acquired from the imaging device 100, theconfiguration of the embodiment of the present invention is not limitedto the above. For example, in a configuration, the SEM image may beacquired from a storage device such as a hard disk in which the SEMimage is stored in advance, or from another system via a network and thelike. In another configuration, in addition to the SEM image,information about imaging conditions and the like corresponding to theSEM image may be acquired and utilized for inspection or measurement. Inyet another configuration, the design data may also be acquired fromanother system via a network and the like instead of from the storagedevice. While in the embodiment the inspection or measurement result isoutput to the display device of the operation terminal, the embodimentof the present invention is not limited to the above. For example, in aconfiguration, the inspection or measurement result may be output to astorage device such as a hard disk, or to another system via a networkand the like.

In the embodiment, because a threshold value method is used fordetermining the length measuring edge, a value corresponding to thethreshold value for the threshold value method is used with regard tothe edge extraction parameter value, too. However, the embodiment of thepresent invention is not limited to the above. For example, when, as alength measuring edge determination method, a first derivation profileis observed to determine the edge position, a value concerning a firstderivation value may also be used for the edge extraction parametervalue too.

In the embodiment, as the contour line used for inspection ormeasurement, a length-measuring contour line is used. However, theembodiment of the present invention is not limited to the above. Forexample, an obtained length-measuring contour line may be discretized toobtain a set of edges defined in pixel units, and then the edge set maybe used for inspection or measurement. In this case, as the informationabout edges with which each pixel is provided, information about a linesegment extending across the pixel (such as sub-pixel accuracy positioninformation about a certain point on the line segment, and vectorinformation indicating the direction of the line segment) may beprovided so as to increase the accuracy of the edge position used forinspection or measurement.

Thus, according to the present invention, an edge extraction parameterfor extracting an edge from image data obtained by imaging an inspectionor measurement object pattern is generated using a reference pattern asa reference for the inspection or measurement and the image data. Then,the inspection or measurement is performed based on the generated edgeextraction parameter and using the edge determined from the image data.Thus, during inspection or measurement using the position of the edgeextracted from the image data obtained by imaging a pattern as theobject of inspection or measurement, the influence of noise and the likecan be decreased, and the reliability of an inspection or measurementresult can be increased.

REFERENCE SIGNS LIST

-   100 Imaging device-   101 SEM-   102 Control device-   110 Operating/processing device-   111 Memory-   112 Initial setting unit-   113 Edge extraction parameter generation unit-   114 Contour line forming unit-   115 Inspection unit-   120 Operation terminal-   130 Storage device-   140 Simulator

The invention claimed is:
 1. A pattern inspecting and measuring devicethat performs inspection or measurement of an inspection or measurementobject pattern using a position of an edge extracted, using an edgeextraction parameter, from image data obtained by imaging the inspectionor measurement object pattern, the pattern inspecting and measuringdevice comprising: a processing device and a non-transitory memorystoring a program, wherein the program, when executed by the processingdevice, causes the processing device to: acquire the image data ofinspection or measurement target pattern, generate a brightness profileof the image data, at each position of multiple different positions on areference pattern as a reference for the inspection or a measurement, ina direction intersecting with the edge of the reference pattern, definean interval for extracting edge extraction parameter of the brightnessprofile with respect to the edge position of the different objectpattern based on the edge of the reference pattern, set the thresholdvalue for each different position, depending on the difference of theposition between the edge of the reference pattern in the defined rangeand the position that extracts from brightness profile, extract a newedge for each different position from the brightness profile using athreshold value set for each different position of the object pattern,compare the edge of the reference pattern and the pattern edge whichgenerates based on the extraction of the new edge and the edge of thereference pattern, and output the comparison results.
 2. The patterninspecting and measuring device according to claim 1, wherein: thereference pattern is configured to include a plurality of referenceedges as a point of reference when extracting the edge; and the patterninspecting and measuring device generates an edge extraction parametercorresponding to each of the reference edges.
 3. The pattern inspectingand measuring device according to claim 2, wherein: the reference edgesare configured to belong to any of pattern figures reflecting a shape ofthe inspection or measurement object pattern; and the pattern inspectingand measuring device generates the edge extraction parameter in such away that edge extraction parameters corresponding to respectivereference edges that belong to the same pattern figure are equal to eachother.
 4. The pattern inspecting and measuring device according to claim2, wherein the pattern inspecting and measuring device generates theedge extraction parameter in such a way that edge extraction parameterscorresponding to the respective reference edges are equal to each other.5. The pattern inspecting and measuring device according to according toclaim 1, wherein the pattern inspecting and measuring device outputs astatistic concerning the generated edge extraction parameter, orconcerning the generated edge extraction parameter.
 6. The patterninspecting and measuring device according to claim 1, wherein thepattern inspecting and measuring device inspects the inspection ormeasurement object pattern using the generated edge extraction parameteras an evaluation index.
 7. The pattern inspecting and measuring deviceaccording to claim 1, wherein the pattern inspecting and measuringdevice inputs a minimum value and a maximum value of values that may betaken by the edge extraction parameter, and generates the edgeextraction parameter in such a way that the edge extraction parameterhas a value not smaller than the minimum value and not greater than themaximum value.
 8. The pattern inspecting and measuring device accordingto claim 1, wherein the pattern inspecting and measuring device inputs amaximum value of deviation from a reference value for the edgeextraction parameter, and generates the edge extraction parameter insuch a way that an absolute value of a difference between the edgeextraction parameter and the reference value is not greater than themaximum deviation.
 9. The pattern inspecting and measuring deviceaccording to claim 1, wherein the pattern inspecting and measuringdevice generates the reference pattern based on a position of an edgeextracted from the image data using a previously given second edgeextraction parameter.
 10. The pattern inspecting and measuring deviceaccording to claim 1, wherein the pattern inspecting and measuringdevice generates the reference pattern based on an edge positionextracted from second image data obtained by imaging a second inspectionor measurement object pattern different from the inspection ormeasurement object pattern in manufacturing process.
 11. The patterninspecting and measuring device according to claim 1, wherein thepattern inspecting and measuring device generates the reference patternbased on an edge position extracted from second image data obtained byimaging a second inspection or measurement object pattern different fromthe inspection or measurement object pattern in an exposure condition.12. The pattern inspecting and measuring device according to claim 1,wherein the inspection or measurement is performed using informationabout a distance between the position of the edge and a position on thereference pattern corresponding to the edge position.
 13. The patterninspecting and measuring device according to claim 1, wherein thereference pattern as a reference for the inspection or measurement isconfigured to include a plurality of reference edges as a point ofreference when extracting the edge, the pattern inspecting and measuringdevice implements, with respect to a portion of the reference edge inwhich the edge corresponding to the reference edge is not present, aprocess of determining the edge used for the inspection or measurementusing a contour line determined with the use of the image data.
 14. Thepattern inspecting and measuring device according to claim 1, wherein:the pattern inspecting and measuring device performs inspection ormeasurement of an inspection or measurement object pattern formed on thesample using image data obtained by imaging a band-like region on asample by a charged particle beam scan; and the charged particle beamscan is performed in a direction inclined with respect to a directionperpendicular to a longitudinal direction of the band-like region. 15.The pattern inspecting and measuring device according to claim 1,wherein: the reference pattern as a reference for the inspection ormeasurement is configured to include a plurality of reference edges as apoint of reference when extracting the edge; and with respect to aprofile generated at a position of each of the reference edges, an edgeis determined using three or more mutually different edge extractionparameters to form a contour line corresponding to each of the edgeextraction parameters, and the inspection or measurement is performedusing the three or more contour lines that are formed.
 16. Anon-transitory computer-readable medium storing executable instructions,the executable instruction when executed by an operating device includedin a pattern inspecting and measuring device performs a method forinspection or measurement of an inspection or measurement object patternusing a position of an edge extracted, with the use of an edgeextraction parameter, from image data obtained by imaging the inspectionor measurement object pattern, the method comprising: acquiring theimage data of inspection or measurement target pattern, generating abrightness profile of the image data, at each position of multipledifferent positions on a reference pattern as a reference for theinspection or a measurement, in a direction intersecting with the edgeof the reference pattern, defining an interval for extracting edgeextraction parameter of the brightness profile with respect to the edgeposition of the different object pattern based on the edge of thereference pattern, setting the threshold value for each differentposition, depending on the difference of the position between the edgeof the reference pattern in the defined range and the position thatextracts from brightness profile, extracting a new edge for eachdifferent position from the brightness profile using a threshold valueset for each different position of the object pattern, comparing theedge of the reference pattern and the pattern edge which generates basedon the extraction of the new edge and the edge of the reference pattern,and outputting the comparison results.